omap: drop v6.12 and default to v6.18

Switch to kernel v6.18 and drop v6.12.

Signed-off-by: Andre Heider <a.heider@gmail.com>
Link: openwrt/openwrt#22728
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

Author: dhewg

target/linux/omap/Makefile

@@ -12,8 +12,7 @@ CPU_TYPE:=cortex-a8
 CPU_SUBTYPE:=vfpv3
 SUBTARGETS:=generic
 
-KERNEL_PATCHVER:=6.12
-KERNEL_TESTING_PATCHVER:=6.18
+KERNEL_PATCHVER:=6.18
 
 KERNELNAME:=zImage dtbs