Libcamera formats are generally little-endian, matching DMA DRM
fourccs, while PW ones are big-endian. Thus we have to invert the
order.
Only RGB and BGR where tested, as these are the formats currently
supported by the software ISP. This fixes inverted red and blue in
Snapshot on the Librem5 and Pinephone (OG).
See also gstlibcamera-utils.cpp in libcamera.