[X86] Add patterns to select (scalar_to_vector (loadf32)) as (V)MOVSSrm...

[X86] Add patterns to select (scalar_to_vector (loadf32)) as (V)MOVSSrm instead of COPY_TO_REGCLASS + (V)MOVSSrm_alt.

Similar for (V)MOVSD. Ultimately, I'd like to see about folding
scalar_to_vector+load to vzload. Which would select as (V)MOVSSrm
so this is closer to that.

llvm-svn: 364948