ar71xx: build kernel modules used by Gluon into the kernel

ar71xx-generic and -tiny benefit most from the optimized kernel, as they
contain all devices with 32MB RAM. We enable CONFIG_GLUON_SPECIALIZE_KERNEL
for all targets using the mips24_kc architecture so packages shared between
targets don't need to be rebuild all the time.

targets/ar71xx-generic

+config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+
 ATH10K_PACKAGES='-kmod-ath10k kmod-ath10k-ct'
 ATH10K_PACKAGES_QCA9887=
 if [ "$GLUON_WLAN_MESH" = 'ibss' ]; then

targets/ar71xx-mikrotik

+config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+
 # Enable ath5k in addition to ath9k
 # ath5k cards are commonly used with Mikrotik hardware
 packages 'kmod-ath5k'

targets/ar71xx-nand

+config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+
 factory -ubi-factory .img
 sysupgrade -squashfs-sysupgrade .tar
 

targets/ar71xx-tiny

+config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+
 no_opkg
 packages '-uboot-envtools' '-kmod-usb-core' '-kmod-usb-ohci' '-kmod-usb2' '-kmod-usb-ledtrig-usbport'