arm64: a37xx: pci: Depends on DM_GPIO

For proper initialization of aardvark pci driver it is required to
de-assert reset GPIO. So depeneds on DM_GPIO option.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Andre Heider <a.heider@gmail.com>