Fix suffix handling for parsing and printing of cvtsi2ss, cvtsi2sd, cvtss2si,...

Fix suffix handling for parsing and printing of cvtsi2ss, cvtsi2sd, cvtss2si, cvttss2si, cvtsd2si, and cvttsd2si to match gas behavior.

cvtsi2* should parse with an 'l' or 'q' suffix or no suffix at all. No suffix should be treated the same as 'l' suffix. Printing should always print a suffix. Previously we didn't parse or print an 'l' suffix.
cvtt*2si/cvt*2si should parse with an 'l' or 'q' suffix or not suffix at all. No suffix should use the destination register size to choose encoding. Printing should not print a suffix.

Original 'l' suffix issue with cvtsi2* pointed out by Michael Kuperstein.

llvm-svn: 171668