at91: put u-boot images into image staging directory

Currently, building at91 subtargets via image builder will fail as the
required built u-boot is not present in the image builder at all since its
presumed to be in the binary directory which obviously does not exist yet.

So, lets install the u-boot binary into image staging directory and use
that instead.

Link: https://github.com/openwrt/openwrt/pull/18414
Signed-off-by: Robert Marko <robimarko@gmail.com>

package/boot/uboot-at91/Makefile

@@ -179,4 +179,9 @@ define Build/Compile
 		$(UBOOT_MAKE_FLAGS)
 endef
 
+define Build/InstallDev
+	$(INSTALL_DIR) $(STAGING_DIR_IMAGE)
+	$(INSTALL_DATA) $(PKG_BUILD_DIR)/$(UBOOT_IMAGE) $(STAGING_DIR_IMAGE)/$(BUILD_VARIANT)-$(UBOOT_IMAGE)
+endef
+
 $(eval $(call BuildPackage/U-Boot))

target/linux/at91/image/sam9x.mk

@@ -16,7 +16,7 @@ define Build/at91-sdcard
 	::$(DEVICE_NAME)-fit.itb
 
   mcopy -i $@.boot \
-	$(BIN_DIR)/u-boot-$(if $(findstring sam9x60,$@),$(DEVICE_DTS:at91-%=%),at91sam9x5ek)_mmc/u-boot.bin \
+	$(STAGING_DIR_IMAGE)/$(if $(findstring sam9x60,$@),$(DEVICE_DTS:at91-%=%),at91sam9x5ek)_mmc-u-boot.bin \
 	::u-boot.bin
 
   mcopy -i $@.boot \

target/linux/at91/image/sama5.mk

@@ -16,7 +16,7 @@ define Build/at91-sdcard
 	::$(DEVICE_NAME)-fit.itb
 
   mcopy -i $@.boot \
-	$(BIN_DIR)/u-boot-$(DEVICE_DTS:at91-%=%)_mmc/u-boot.bin \
+	$(STAGING_DIR_IMAGE)/$(DEVICE_DTS:at91-%=%)_mmc-u-boot.bin \
 	::u-boot.bin
 
   $(if $(findstring sama5d4-xplained,$@), \

target/linux/at91/image/sama7.mk

@@ -16,7 +16,7 @@ define Build/at91-sdcard
 	::$(DEVICE_NAME)-fit.itb
 
   mcopy -i $@.boot \
-	$(BIN_DIR)/u-boot-$(DEVICE_DTS:at91-%=%)_mmc1/u-boot.bin \
+	$(STAGING_DIR_IMAGE)/$(DEVICE_DTS:at91-%=%)_mmc1-u-boot.bin \
 	::u-boot.bin
 
   mcopy -i $@.boot \