gpio/hsdk: Depend on DM_GPIO instead of simple DM

gpio/hsdk: Depend on DM_GPIO instead of simple DM

This driver really is DM GPIO one and so we need to have a correct
dependency, because DM alone doesn't provide required for CMD_GPIO
call and we're seeing build failures like this:
---------------------->8---------------------
cmd/built-in.o: In function 'do_gpio':
.../cmd/gpio.c:188: undefined reference to 'gpio_request'
...
---------------------->8---------------------

Signed-off-by: Alexey Brodkin <[email protected]>
Cc: Eugeniy Paltsev <[email protected]>
Cc: Simon Glass <[email protected]>
Reviewed-by: Simon Glass <[email protected]>