MIPS: BCM47xx: Select GPIOLIB for BCMA on bcm47xx platform

The Kconfig items BCM47XX_BCMA and BCM47XX_SSB selected respectively
BCMA_DRIVER_GPIO and SSB_DRIVER_GPIO. These options depend on GPIOLIB
without explicitly selecting it so it results in a warning when GPIOLIB
is not set:

scripts/kconfig/conf --oldconfig Kconfig
warning: (BCM47XX_BCMA) selects BCMA_DRIVER_GPIO ... unmet direct
	dependencies (BCMA_POSSIBLE && BCMA && GPIOLIB)
warning: (BCM47XX_SSB) selects SSB_DRIVER_GPIO ... unmet direct
	dependencies (SSB_POSSIBLE && SSB && GPIOLIB)

which subsequently results in compile errors.

Signed-off-by: Arend van Spriel <arend@broadcom.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4759/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/bcm47xx/Kconfig

@@ -10,6 +10,7 @@ config BCM47XX_SSB
 	select SSB_B43_PCI_BRIDGE if PCI
 	select SSB_PCICORE_HOSTMODE if PCI
 	select SSB_DRIVER_GPIO
+	select GPIOLIB
 	default y
 	help
 	 Add support for old Broadcom BCM47xx boards with Sonics Silicon Backplane support.
@@ -25,6 +26,7 @@ config BCM47XX_BCMA
 	select BCMA_HOST_PCI if PCI
 	select BCMA_DRIVER_PCI_HOSTMODE if PCI
 	select BCMA_DRIVER_GPIO
+	select GPIOLIB
 	default y
 	help
 	 Add support for new Broadcom BCM47xx boards with Broadcom specific Advanced Microcontroller Bus.