media: ti-vpe: cal: Turn reg_(read|write)_field() into inline functions

Turn the reg_(read|write)_field() macros into inline functions for
additional type safety. Use the FIELD_GET() and FIELD_PREP() macros
internally instead of reinventing the wheel.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>