This fixes building for arm after 10c2ef1c.
The argument to av_clip_uintp2 must be an assembly time immediate
constant.
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Reviewed-by and commit message details-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>