vdpau: restore compatibility with deprecated fields in AVVDPAUContext

Fixes ticket #3133.

Signed-off-by: Hendrik Leppkes <h.leppkes@gmail.com>
Tested-by: EricV
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Cast signed libopenjpeg data values to unsigned before shifting.

This avoids undefined behaviour on left-shift.

Reviewed-by: Michael Bradshaw