msm8226-common: change usbdisk write permissions

Users are not able to write to /storage/usbdisk0
because they are not part of the media_rw (1023) group.
Removing the write restriction allows users to write to
usbdisk without root elevation.

Change-Id: I33177c167aa2e7a58b2a4bcae17e72c93ba7599a
Merge "msm8226-common: change usbdisk write permissions" into cm-11.0