[media] wl128x: fix build errors when GPIOLIB is not enabled
From: Randy Dunlap <rdunlap@xenotime.net>
Fix wl128x Kconfig to depend on GPIOLIB since TI_ST also
depends on GPIOLIB.
(.text+0xe6d60): undefined reference to `st_register'
(.text+0xe7016): undefined reference to `st_unregister'
(.text+0xe70ce): undefined reference to `st_unregister'