avcodec/jpeg2000dec: Check nonzerobits more completely

Fixes: runtime error: shift exponent 36 is too large for 32-bit type 'int'
Fixes: 2239/clusterfuzz-testcase-minimized-5639766592716800

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg


Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>