media: ov5645: Use regulator_bulk() functions

The code can be simplified by using the regulator_bulk() functions,
so switch to it.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>