[X86] Correct scheduler information for rotate by constant for Haswell, Broadwell...

[X86] Correct scheduler information for rotate by constant for Haswell, Broadwell, and Skylake.

Rotate with explicit immediate is a single uop from Haswell on. An immediate of 1 has a dependency on the previous writer of flags, but the other immediate values do not.

The implicit rotate by 1 instruction is 2 uops. But the flags are merged after the rotate uop so the data result does not see the flag dependency. But I don't think we have any way of modeling that.

RORX is 1 uop without the load. 2 uops with the load. We currently model these with WriteShift/WriteShiftLd.

Differential Revision: https://reviews.llvm.org/D59077

llvm-svn: 355636