[mips][msa] Added support for matching bins[lr]i.[bhwd] from normal IR (i.e. not intrinsics)

This required correcting the definition of the bins[lr]i intrinsics because
the result is also the first operand.

It also required removing the (arbitrary) check for 32-bit immediates in
MipsSEDAGToDAGISel::selectVSplat().

Currently using binsli.d with 2 bits set in the mask doesn't select binsli.d
because the constant is legalized into a ConstantPool. Similar things can
happen with binsri.d with more than 10 bits set in the mask. The resulting
code when this happens is correct but not optimal.

llvm-svn: 193687