dlx: external storage (usb-otg) ala 4.4

Setup according to (like Xoom):

http://source.android.com/devices/tech/storage/config-example.html

except I maintained our use of "usbdisk" instead of "sdcard1".

Change-Id: Ic779c5eb80bb0c4ba87323d7033bcffed1923275
Merge branch 'cm-11.0' into martincz