The driver currently only implements the Rec. 601 YCbCr encoding, extend
it with support for the other encodings defined by V4L2 (Rec. 709, Rec.
2020 and SMPTE240m). The coefficients have been calculated by rounding
the floating point values to the nearest Q1.7 fixed-point value,
adjusting the rounding to ensure that the sum of each line in the matrix
is preserved to avoid overflows.

At the hardware level, the RGB to YUV conversion matrix is fully
configurable, custom encoding could be supported by extending the ISP
parameters if desired.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Dafna Hirschfeld <dafna@fastmail.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>