x86/Intel: allow MASM representation of embedded broadcast

x86/Intel: allow MASM representation of embedded broadcast

MASM doesn't support the {1to<n>} form; DWORD BCST (paralleling
DWORD PTR) and alike are to be used there instead. Accept these forms
alongside the original (now legacy) ones.

Acceptance of the original {1to<n>} operand suffix is retained both for
backwards compatibility and to disambiguate VFPCLASSP{S,D,H} and vector
conversions with shrinking element sizes. I have no insight (yet) into
how MASM expects those to be disambiguated.

Adjust some, but not all of the testcases.