m7-common: remove legacy CWM hack

Change-Id: I6b7ea9a6da979992a95d0e4db560327fd0c999de
m7-common: remove discard option

Change-Id: I33317a5f8bc302986137af4361c1eff43cd222cf
Merge remote-tracking branch 'upstream/cm-10.2' into cm-10.2