airoha: default to kernel 6.6

Move airoha do kernel 6.6 as the default.

Link: https://github.com/openwrt/openwrt/pull/15630
Signed-off-by: Robert Marko <[email protected]>

target/linux/airoha/Makefile

@@ -6,8 +6,7 @@ BOARDNAME:=Airoha ARM
 CPU_TYPE:=cortex-a7
 FEATURES:=dt squashfs nand ramdisk gpio source-only
 
-KERNEL_PATCHVER:=6.1
-KERNEL_TESTING_PATCHVER:=6.6
+KERNEL_PATCHVER:=6.6
 
 include $(INCLUDE_DIR)/target.mk