media: staging: rkisp1: cap: change RGB24 format to XBGR32

According to the TRM [1], the YUV->RGB conversion outputs
RGB 888 format with 4 bytes, where the last byte is ignored,
using big endian representation:

|___X___|___R___|___G___|___B___|
31      24      16      8       0

Which matches format V4L2_PIX_FMT_XBGR32 in little endian
representation, so replace it accordingly.

"24 bit word". What it means is that 4 bytes are used with
24bit for the RGB and the last byte is ignored.
This matches format V4L2_PIX_FMT_XBGR32.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>