media: ti: j721e-csi2rx: add support for RGB formats

Add support for RGB565, RGB888 and BGR888 media bus formats.

The pixel formats for these have a different byte-order than the MIPI
bus formats, given the SHIM IP [1] unpacks them into memory as follows:

MIPI RGB888 unpacks to:
BYTE3		BYTE2		BYTE1		BYTE0
00000000	RRRRRRRR	GGGGGGGG	BBBBBBBB

MIPI RGB565 unpacks to:
BIT 15-11	BIT 10-5	BIT 4-0
RRRRR		GGGGGG		BBBBB

[1]: AM62x TRM: 12.6.1.4.5 "CSI_RX_IF Data Memory Organization Details"

Link: https://www.ti.com/lit/pdf/spruiv7


Signed-off-by: Jai Luthra <j-luthra@ti.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>