selfie cam: fix buffer to have 2bpp from (mipi) raw10
this might (if not only) be an issue to solve at the SoC CSI side. The buffers are being filled with 8bits per pixel and since 2 bytes per pixels are reserved for raw10 in mx6s_capture, we get 2 frames in 1 buffer (at least in 640x480 mode, 2 full images). See also https://source.puri.sm/Librem5/linux-next/-/issues/43#note_145151 and last few posts in that issue.
in modes 1280x720 and higher with each subsequent captured frame, the image itself shifts and cropping at 720 results in the lower part of the image on top and a higher part below!
this problems is posted to the NXP community forums too: https://community.nxp.com/t5/i-MX-Processors/imx8mq-csi-raw10-rx-problem/td-p/1239329
note that raw10 on the mipi side is 4 pixels in 5 bytes (5th bytes having the remaining 4x2bits).