rockchip: switch to 5.15 kernel

Run tested: NanoPI R4S

Signed-off-by: Tomas Lara <[email protected]>

target/linux/rockchip/Makefile

@@ -7,8 +7,7 @@ BOARDNAME:=Rockchip
 FEATURES:=ext4 audio usb usbgadget display gpio fpu pci pcie rootfs-part boot-part squashfs
 SUBTARGETS:=armv8
 
-KERNEL_PATCHVER:=5.10
-KERNEL_TESTING_PATCHVER:=5.15
+KERNEL_PATCHVER:=5.15
 
 define Target/Description
 	Build firmware image for Rockchip SoC devices.