lossless_videodsp.asm: fix compilation.

Fixes these errors with nasm:
libavcodec/x86/lossless_videodsp.asm:86: error: invalid combination of opcode and operands
libavcodec/x86/lossless_videodsp.asm:88: error: invalid combination of opcode and operands
I don't know whether movd or movq was meant, but either way
maskq vs. maskd must match the mov size.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
