[InstSimplify] Push commuted op checks for and/or of icmp further down to avoid duplicate work

Previously, we called simplifyPossiblyCastedAndOrOfICmps twice with the operands commuted, but the call to simplifyAndOrOfICmpsWithConstants further down already handles commuting and doesn't need to be called both ways.

This patch pushes double calls further down to just the individual routines that need to be called twice.

Differential Revision: https://reviews.llvm.org/D33603

llvm-svn: 304044