[X86] Add isel patterns to be able to fold loads into VPERM2F128 even when the...

[X86] Add isel patterns to be able to fold loads into VPERM2F128 even when the load is on the first input to the SDNode.

We just need to toggle bits 1 and 5 of the immediate and swap the sources. The peephole pass could trigger commuting/folding for this later, but its easy enough to fix in isel.

Disable the peephole pass on the main vperm2x128 test so we know we're doing this through isel.

llvm-svn: 313455