[SVE] Fix crashes with inline assembly
All the crashes found compiling inline assembly are fixed in this
patch by changing AArch64TargetLowering::getRegForInlineAsmConstraint
to be more resilient to mismatched value and register types. For
example, it makes no sense to request a predicate register for
a nxv2i64 type and so on.
Tests have been added here:
Differential Revision: https://reviews.llvm.org/D92554