mpc85xx: p1010: make TP-Link WDR4900 v1 build again

Add the spi-loader as a pre-kernel stage, so we can lift the kernel size
limit.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
(cherry picked from commit 2fa53c9)

target/linux/mpc85xx/image/p1010.mk

@@ -1,5 +1,19 @@
 DEVICE_VARS += TPLINK_HWID TPLINK_HWREV TPLINK_FLASHLAYOUT TPLINK_HEADER_VERSION
 
+define Build/spi-loader-okli-compile
+	rm -rf $@.spi-loader-okli
+	$(CP) spi-loader $@.spi-loader-okli
+	$(MAKE) -C $@.spi-loader-okli \
+		CROSS_COMPILE="$(TARGET_CROSS)" CONFIG="$(DEVICE_NAME)"
+	cp "$@.spi-loader-okli/out/uImage" "$@"
+	rm -rf $@.spi-loader-okli
+endef
+
+define Build/spi-loader-okli
+	cat $(KDIR)/loader-$(1) "$@" > "$@.new"
+	mv "$@.new" "$@"
+endef
+
 define Device/tplink_tl-wdr4900-v1
   DEVICE_VENDOR := TP-Link
   DEVICE_MODEL := TL-WDR4900
@@ -8,19 +22,19 @@ define Device/tplink_tl-wdr4900-v1
   TPLINK_HWID := 0x49000001
   TPLINK_HWREV := 1
   TPLINK_FLASHLAYOUT := 16Mppc
-  KERNEL_SIZE := 2684k
   KERNEL_NAME := simpleImage.tl-wdr4900-v1
   KERNEL_INITRAMFS :=
-  KERNEL := kernel-bin | uImage none
+  KERNEL := kernel-bin | uImage none -M 0x4f4b4c49 | spi-loader-okli $(1)
   KERNEL_ENTRY := 0x1000000
   KERNEL_LOADADDR := 0x1000000
   SUPPORTED_DEVICES += tl-wdr4900-v1
+  COMPILE := loader-$(1)
+  COMPILE/loader-$(1) := spi-loader-okli-compile
   ARTIFACTS := fdt.bin
   ARTIFACT/fdt.bin := append-dtb
   IMAGES := factory.bin sysupgrade.bin
   IMAGE/sysupgrade.bin := tplink-v1-image sysupgrade | append-metadata
   IMAGE/factory.bin := tplink-v1-image factory
-  DEFAULT := n
 endef
 TARGET_DEVICES += tplink_tl-wdr4900-v1