Hexagon HVX (target/hexagon) import macro definitions

Hexagon HVX (target/hexagon) import macro definitions

Imported from the Hexagon architecture library
    imported/allext_macros.def       Top level macro include for all extensions
    imported/macros.def              Scalar core macros (some HVX here)
    imported/mmvec/macros.def        HVX macro definitions
The macro definition files specify instruction attributes that are applied
to each instruction that reverences the macro.

Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>