ARM: davinci: da850 evm: register uio_pruss device

Registers the uio_pruss platform device on the DA850 EVM.

Tested on AM180x-EVM using the PRU_memAccessPRUDataRam and
PRU_memAccessL3andDDR examples from the PRU userspace tools
available from http://www.ti.com/tool/sprc940



Signed-off-by: Matt Porter <mporter@ti.com>
[nsekhar@ti.com: use pr_warn() instead of pr_warning()]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>