[ARM] Fix assembly and disassembly for VMRS/VMSR
This patch addresses two issues with assembly and disassembly for VMRS/VMSR:
1.currently VMRS/VMSR instructions accessing fpsid, mvfr{0-2} and fpexc, are
accepted for non ARMv8-A targets.
2. all VMRS/VMSR instructions accept writing/reading to PC and SP, when only
ARMv7-A and ARMv8-A should be allowed to write/read to SP and none to PC.
This patch addresses those issues and adds tests for these cases.
Differential Revision: https://reviews.llvm.org/D36306
llvm-svn: 310243