ARM: mvebu: select ARCH_REQUIRE_GPIOLIB for mvebu platform

Initially ARCH_REQUIRE_GPIOLIB was part of Thomas Petazzoni series
when he introduced the gpiolib support for mvebu:
93a59cf arm: mvebu: use GPIO support now that a driver is available

This commit was written to be applied for the ARCH_MVEBU which was
located in arch/arm/KConfig and was merged in 3.7.

In the same time Rob Herring moved the ARCH_MVEBU block to
arch/arm/mach-mvebu/Kconfig with this commit and also merged in 3.7:
387798b ARM: initial multiplatform support

Unfortunately the ARCH_REQUIRE_GPIOLIB have been lost during this
migration. This was not noticed until the v3.10-rc1, because mvebu as
part of ARCH_MULTIPLATFORM was always selected with ARCH_VEXPRESS, and
this architect selected ARCH_REQUIRE_GPIOLIB.

Since the following commit from Arnd: "883a106 ARM: default machine
descriptor for multiplatform", ARCH_VEXPRESS was then no more selected
by default with ARCH_MVEBU and it made appeared the lack of
ARCH_REQUIRE_GPIOLIB for mvebu. This commit added back the selection
of ARCH_REQUIRE_GPIOLIB for ARCH_MVEBU.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/mach-mvebu/Kconfig

@@ -15,6 +15,7 @@ config ARCH_MVEBU
 	select MVEBU_CLK_GATING
 	select MVEBU_MBUS
 	select ZONE_DMA if ARM_LPAE
+	select ARCH_REQUIRE_GPIOLIB
 
 if ARCH_MVEBU