ARM assembly parsing for register range syntax for VLD/VST register lists.

For example,
vld1.f64 {d2-d5}, [r2,:128]!

Should be equivalent to:
vld1.f64 {d2,d3,d4,d5}, [r2,:128]!

It's not documented syntax in the ARM ARM, but it is consistent with what's
accepted for VLDM/VSTM and is unambiguous in meaning, so it's a good thing to
support.

rdar://10451128

llvm-svn: 144727