Turn on PRUSS driver for AM335x PRUs
Turn on PRUSS driver for AM335x PRUs

The UIO_PRUSS driver was for earlier TI processors and isn't enabled in
the AM3358 EVM SK configuration. This turns that one off and enables th
PRUSS driver for the AM335x PRUs.

nerves-project/nerves_system_bbb,nerves-project/nerves_system_bbb