vp8,vpx_dsp:[loongson] fix specification of instruction name

1.'xor,or,and' to 'pxor,por,pand'. In the case of operating FPR,
  gcc supports both of them, clang only supports the second type.
2.'dsrl,srl' to 'ssrld,ssrlw'. In the case of operating FPR, gcc
  supports both of them, clang only supports the second type.

Change-Id: I93b47348e7c6580d99f57dc11165b4645236533c
11 files changed