system.prop: remove duplicate line

Change-Id: I6af9e3e1312bd9fa03d6f1310cc1fcc341550128
system.prop: cleanup take 2

Change-Id: I3d65a54ae8ba0cc7b7aa0bda91ad57fbe1c24f41
system.prop: increase wifi scan interval

Change-Id: I45e525a80a72383c885bafd9acd732c3bdba3216