brcm63xx: switch to 4.14

Kernel 4.14 support has been present for quite some time, so let's give
it wider testing.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

target/linux/brcm63xx/Makefile

@@ -12,7 +12,7 @@ BOARD:=brcm63xx
 BOARDNAME:=Broadcom BCM63xx
 SUBTARGETS:=generic smp
 FEATURES:=squashfs usb atm pci pcmcia usbgadget
-KERNEL_PATCHVER:=4.9
+KERNEL_PATCHVER:=4.14
 MAINTAINER:=Jonas Gorski <jogo@openwrt.org>
 
 define Target/Description