p1-common: use mtp instead mass_storage

actually mass storage isn't supported on omnirom
so set mtp as well

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: I3491be6f0568b66713ebc95bd10e8c11fec28b41
Merge "p1-common: use mtp instead mass_storage" into android-4.4