arm64: qcom: enable GPIOLIB in Kconfig

While debugging a kernel image size issue, I discovered that if all
non ARCH_QCOM configs in the ARM64 defconfig are disabled, the QCOM
pinctrl drivers will not be built.

The QCOM pinctrl drivers have a dependency on GPIOLIB which was being
selected when other ARCH configs were enabled, but ARCH_QCOM doesn't
select GPIOLIB directly.  Let's select GPIOLIB here to ensure the pinctrl
drivers are built for QCOM platforms.

Signed-off-by: Michael Scott <michael.scott@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>