airoha: move en7523 in dedicated subtarget

In preparation for EN7581 SoC support, move en7523 in dedicated
subtarget.

This is needed as EN7581 is now 64bit but en7523 is 32bit hence have
very different kernel config.

Also rename patch to a more friendly number sequence.

Link: https://github.com/openwrt/openwrt/pull/16730
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

target/linux/airoha/Makefile

@@ -3,13 +3,11 @@ include $(TOPDIR)/rules.mk
 ARCH:=arm
 BOARD:=airoha
 BOARDNAME:=Airoha ARM
-CPU_TYPE:=cortex-a7
+SUBTARGETS:=en7523
 FEATURES:=dt squashfs nand ramdisk gpio source-only
 
 KERNEL_PATCHVER:=6.6
 
 include $(INCLUDE_DIR)/target.mk
 
-KERNELNAME:=Image dtbs
-
 $(eval $(call BuildTarget))

target/linux/airoha/en7523/target.mk

@@ -0,0 +1,6 @@
+ARCH:=arm
+SUBTARGET:=en7523
+BOARDNAME:=EN7523
+CPU_TYPE:=cortex-a7
+KERNELNAME:=Image dtbs
+FEATURES+=source-only

target/linux/airoha/generic/target.mk

@@ -1 +0,0 @@
-BOARDNAME:=Generic

target/linux/airoha/image/Makefile

@@ -1,12 +1,6 @@
 include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/image.mk
 
-KERNEL_LOADADDR := 0x80208000
-
-define Target/Description
-	Build firmware images for Airoha EN7523 ARM based boards.
-endef
-
 # default all platform image(fit) build
 define Device/Default
   PROFILES = Default $$(DEVICE_NAME)
@@ -22,16 +16,10 @@ define Device/Default
 	pad-rootfs | append-metadata
 endef
 
+include $(SUBTARGET).mk
+
 define Image/Build
 	$(call Image/Build/$(1),$(1))
 endef
 
-define Device/airoha_en7523-evb
-  DEVICE_VENDOR := Airoha
-  DEVICE_MODEL := EN7523 Evaluation Board
-  DEVICE_DTS := en7523-evb
-  DEVICE_DTS_DIR := ../dts
-endef
-TARGET_DEVICES += airoha_en7523-evb
-
 $(eval $(call BuildImage))

target/linux/airoha/image/en7523.mk

@@ -0,0 +1,13 @@
+KERNEL_LOADADDR := 0x80208000
+
+define Target/Description
+	Build firmware images for Airoha EN7523 ARM based boards.
+endef
+
+define Device/airoha_en7523-evb
+  DEVICE_VENDOR := Airoha
+  DEVICE_MODEL := EN7523 Evaluation Board
+  DEVICE_DTS := en7523-evb
+  DEVICE_DTS_DIR := ../dts
+endef
+TARGET_DEVICES += airoha_en7523-evb