Mul simplification should expect zero operand

It is possible that zero constant can appear due to
simplification of other instructions, so we cannot expect
zero handling from constant optimizations.

Change-Id: I084126fd0c106ac2683c4f10a451960d9807f4f6
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
4 files changed