Currently the LLVM MC assembler is able to convert e.g.
vmov.i32 d0, #0xabababab
(which is technically invalid) into a valid instruction
vmov.i8 d0, #0xab
this patch adds support for vmov.i64 and for cases with the resulting
load types other than i8, e.g.:
vmov.i32 d0, #0xab00ab00 -> vmov.i16 d0, #0xab00