Fix LLDB elf core dump register access for ARM/AArch64
This patch adds support to access AArch64 FP SIMD core dump registers and adds a test case to verify registers.
This patches fixes a bug where doing "register read --all" causes lldb to crash.
Reviewed By: labath
Subscribers: kristof.beyls, danielkiss, lldb-commits
Differential Revision: https://reviews.llvm.org/D77793