media: atomisp: use read/write routines from mainstream

There is an ov2680 driver mainstream. Use the read/write
routines from it, as the ones inside this driver are
generating some errors:

	ov2680 i2c-OVTI2680:00: ov2680_i2c_write: i2c write reg=0x3086, value 0x00, error -121

Maybe the code that changes from/to BE are not right.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>