[AArch64][AsmParser] Make parse function for VectorLists generic to other vector types.

Summary:
Added 'RegisterKind' to the VectorListOp structure, so that this operand 
type can be reused for SVE vector lists in a later patch. It also
refactors the 'tryParseVectorList' function so it can be used directly
in the ParserMethod of an operand. The parsing can now parse multiple 
kinds of vectors and recover if there is no match.

This is patch [3/6] in a series to add assembler/disassembler support for
SVE's contiguous ST1 (scalar+imm) instructions.

Reviewers: fhahn, rengolin, javed.absar, huntergr, SjoerdMeijer, t.p.northover, echristo, evandro

Reviewed By: rengolin

Subscribers: kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D45429

llvm-svn: 329900