media: i2c: ak7375: Add regulator management

Make the driver get needed regulators on probe and enable/disable
them on runtime PM callbacks.

Signed-off-by: Yassine Oudjana <y.oudjana@protonmail.com>
Tested-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>