chmod: Fix for displaying help

Validate options and number of argument to display help

Change-Id: Ia003bd362c44d5d868e68f45c7dcfea50864dc7b
CRs-Fixed: 589737
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_system_core into kk44
Merge branch 'kk44' of https://github.com/scotthartbti/platform_system_core into kk44