platform/x86: int3472/discrete: Move GPIO request to skl_int3472_register_clock()

Move the requesting of the clk-enable GPIO to skl_int3472_register_clock()
(and move the gpiod_put to unregister).

This mirrors the GPIO handling in skl_int3472_register_regulator() and
allows removing skl_int3472_map_gpio_to_clk() from discrete.c.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Link: https://lore.kernel.org/r/20230127203729.10205-5-hdegoede@redhat.com