ath79: switch default kernel to 6.12

We have not received any negative feedback in the past three months.
It's time to switch the default kernel to 6.12.

Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19821
Signed-off-by: Nick Hainke <[email protected]>

target/linux/ath79/Makefile

@@ -8,8 +8,7 @@ SUBTARGETS:=generic mikrotik nand tiny
 
 FEATURES:=ramdisk squashfs usbgadget
 
-KERNEL_PATCHVER:=6.6
-KERNEL_TESTING_PATCHVER:=6.12
+KERNEL_PATCHVER:=6.12
 
 include $(INCLUDE_DIR)/target.mk