media: core: add ov_16bit_addr_reg_helpers.h

media: core: add ov_16bit_addr_reg_helpers.h

The following drivers under drivers/media/i2c: ov08x40.c, ov13858.c,
ov13b10.c, ov2680.c, ov2685.c, ov2740.c, ov4689.c, ov5670.c,
ov5675.c, ov5695.c, ov8856.c, ov9282.c and ov9734.c,

as well as various "atomisp" sensor drivers in drivers/staging, *all*
use register access helpers with the following function prototypes:

int ovxxxx_read_reg(struct ovxxxx_dev *sensor, u16 reg,
                    unsigned int len, u32 *val);

int ovxxxx_write_reg(struct ovxxxx_dev *sensor, u16 reg,
                     unsigned int len, u32 val);

To read/write registers on Omnivision OVxxxx image sensors wich expect
a 16 bit register address in big-endian format and which have 1-3 byte
wide registers, in big-endian format (for the higher width registers).

Add a new ov_16bit_addr_reg_helpers.h header file with static inline
versions of these register access helpers, so that this code duplication
can be removed.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>