an 8-bit immediate. So mark the shifts that take immediates as taking
an 8-bit argument. The rest with the implicit use of CL are marked
appropriately.

A bug still exists:

def SHLDmri32  : I2A8 <"shld", 0xA4, MRMDestMem>, TB;           // [mem32] <<= [mem32],R32 imm8

The immediate in the above instruction is 8-bit but the memory
reference is 32-bit. The printer prints this as an 8-bit reference
which confuses the assembler. Same with SHRDmri32.

llvm-svn: 11931