Tell the VExpress bootloader to turn off the USB debug mode once we have done whatever we are going to do with it.
Reduces USB load on the dispatcher.

Added expect for bootloader prompt

Change-Id: I3397b768acadd0cebed52601f6974e5703540310
selinux: test all images for selinux support

Change-Id: Ic366761e5a18bf87ecab23bf948cbd6bfec92edb