riscv: Correct SPARSEMEM configuration

There are two issues for RV32,
1) if use FLATMEM, it is useless to enable SPARSEMEM_STATIC.
2) if use SPARSMEM, both SPARSEMEM_VMEMMAP and SPARSEMEM_STATIC is enabled.

Fixes: d95f1a5 ("RISC-V: Implement sparsemem")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -93,7 +93,6 @@ config RISCV
  select PCI_MSI if PCI
  select RISCV_INTC
  select RISCV_TIMER if RISCV_SBI
- select SPARSEMEM_STATIC if 32BIT
  select SPARSE_IRQ
  select SYSCTL_EXCEPTION_TRACE
  select THREAD_INFO_IN_TASK
@@ -154,7 +153,8 @@ config ARCH_FLATMEM_ENABLE
 config ARCH_SPARSEMEM_ENABLE
  def_bool y
  depends on MMU
- select SPARSEMEM_VMEMMAP_ENABLE
+ select SPARSEMEM_STATIC if 32BIT && SPARSMEM
+ select SPARSEMEM_VMEMMAP_ENABLE if 64BIT
 
 config ARCH_SELECT_MEMORY_MODEL
  def_bool ARCH_SPARSEMEM_ENABLE