Add support for h.264 levels 5 and 5.1

[dustinkerstein]

For soon to be released firmware update by 6by9. See https://www.raspberrypi.org/forums/viewtopic.php?p=1762548#p1762548 for more details. Level specs based on https://www.itu.int/rec/T-REC-H.264-201906-I

[phaseOne]

@dustinkerstein have you tested this with 1920x1440 video capture, and does it work?

Did 6by9 merge their patch? The libcamera-vid app documentation also seems to indicate that only levels 4, 4.1, and 4.2 are available. So I'm thinking the answer is no.

[6by9]

The firmware patch to allow selection of levels 5.0 and 5.1 was merged.

There was a thread recently at https://forums.raspberrypi.com/viewtopic.php?p=1984364#p1984364 where I looked at increasing the resolution beyond the 8192 macroblock/frame limit of level 4.1, and it gives corruption in the macroblocks that exceed that limit. If it doesn't work, then there is little point in enabling it.