usb: gadget: add support for multiple LUNs

Change-Id: I9790007b65a749af2169f3858ffd32a1d616490f
msm: HTC: fighter: give LUN paths to both storage drives

Change-Id: I4e9a8d2bbd9d790e79f62a470d0bebe917b5abb7
msm: HTC: jet: give LUN paths to both storage drives

Change-Id: I8be681883015dc872664745f0ba86ea0b739a698