media: atomisp_gmin_platform: Fix axp_regulator_set() writing to the wrong register

The second write done in axp_regulator_set() must go to the ctrl_reg which
turns the various regulators on/off. This replaces the second write
writing the sel_reg, which sets the voltage for the regulator, for a
second time with a wrong value.

Link: https://lore.kernel.org/linux-media/20220116215204.307649-5-hdegoede@redhat.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>