mmc: Kconfig: Add dependency on GPIOLIB for Arasan driver

The patch "mmc: sdhci-of-arasan: Call OF parsing for MMC"
(sha1: 16b23787) introduce new
dependency on GPIOLIB which calls mmc_of_parse() ->
mmc_gpiod_request_cd() (slot-gpio.c) which calls devm_gpiod_get_index()
which returns -ENOSYS.

Error log:
sdhci-arasan ff160000.sdhci: parsing dt failed (4294967258)
sdhci-arasan: probe of ff160000.sdhci failed with error -38

Signed-off-by: Michal Simek <michal.simek@xilinx.com>