drm: Revert syncobj timeline changes.

Daniel suggested I submit this, since we're still seeing regressions
from it.  This is a revert to before 48197bc ("drm: add syncobj
timeline support v9") and its followon fixes.

Fixes this on first V3D testcase execution:

[   48.767088] ============================================
[   48.772410] WARNING: possible recursive locking detected
[   48.777739] 4.19.0-rc6+ torvalds#489 Not tainted
[   48.781668] --------------------------------------------
[   48.786993] shader_runner/3284 is trying to acquire lock:
[   48.792408] ce309d7f (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.800714]
[   48.800714] but task is already holding lock:
[   48.806559] c5952bd3 (&(&array->lock)->rlock){....}, at: dma_fence_add_callback+0x30/0x23c
[   48.814862]
[   48.814862] other info that might help us debug this:
[   48.821410]  Possible unsafe locking scenario:
[   48.821410]
[   48.827338]        CPU0
[   48.829788]        ----
[   48.832239]   lock(&(&array->lock)->rlock);
[   48.836434]   lock(&(&array->lock)->rlock);
[   48.840640]
[   48.840640]  *** DEADLOCK ***
[   48.840640]
[   48.846582]  May be due to missing lock nesting notation
[  130.763560] 1 lock held by cts-runner/3270:
[  130.767745]  #0: 7834b793 (&(&array->lock)->rlock){-...}, at: dma_fence_add_callback+0x30/0x23c
[  130.776461]
               stack backtrace:
[  130.780825] CPU: 1 PID: 3270 Comm: cts-runner Not tainted 4.19.0-rc6+ torvalds#486
[  130.787706] Hardware name: Broadcom STB (Flattened Device Tree)
[  130.793645] [<c021269c>] (unwind_backtrace) from [<c020db1c>] (show_stack+0x10/0x14)
[  130.801404] [<c020db1c>] (show_stack) from [<c0c2c4b0>] (dump_stack+0xa8/0xd4)
[  130.808642] [<c0c2c4b0>] (dump_stack) from [<c0281a84>] (__lock_acquire+0x848/0x1a68)
[  130.816483] [<c0281a84>] (__lock_acquire) from [<c02835d8>] (lock_acquire+0xd8/0x22c)
[  130.824326] [<c02835d8>] (lock_acquire) from [<c0c49948>] (_raw_spin_lock_irqsave+0x54/0x68)
[  130.832777] [<c0c49948>] (_raw_spin_lock_irqsave) from [<c086bf54>] (dma_fence_add_callback+0x30/0x23c)
[  130.842183] [<c086bf54>] (dma_fence_add_callback) from [<c086d4c8>] (dma_fence_array_enable_signaling+0x58/0xec)
[  130.852371] [<c086d4c8>] (dma_fence_array_enable_signaling) from [<c086c00c>] (dma_fence_add_callback+0xe8/0x23c)
[  130.862647] [<c086c00c>] (dma_fence_add_callback) from [<c06d8774>] (drm_syncobj_wait_ioctl+0x518/0x614)
[  130.872143] [<c06d8774>] (drm_syncobj_wait_ioctl) from [<c06b8458>] (drm_ioctl_kernel+0xb0/0xf0)
[  130.880940] [<c06b8458>] (drm_ioctl_kernel) from [<c06b8818>] (drm_ioctl+0x1d8/0x390)
[  130.888782] [<c06b8818>] (drm_ioctl) from [<c03a4510>] (do_vfs_ioctl+0xb0/0x8ac)
[  130.896187] [<c03a4510>] (do_vfs_ioctl) from [<c03a4d40>] (ksys_ioctl+0x34/0x60)
[  130.903593] [<c03a4d40>] (ksys_ioctl) from [<c0201000>] (ret_fast_syscall+0x0/0x28)

Cc: Chunming Zhou <david1.zhou@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/261044/