SystemUI: Use material delete icon

Change-Id: I11df5713486672e4f5c4784e6f94a893cf36b4dd
Merge remote-tracking branch 'cm/cm-12.0' into HEAD

Conflicts:
	packages/SystemUI/res/drawable-hdpi/ic_menu_delete.png
	packages/SystemUI/res/drawable-mdpi/ic_menu_delete.png
	packages/SystemUI/res/drawable-xhdpi/ic_menu_delete.png
	packages/SystemUI/res/drawable-xxhdpi/ic_menu_delete.png

Change-Id: I606a7073fd3fcebf59535c9c85bd968cb502b1f6