ARM: dts: Add am335x-boneblue

ARM: dts: Add am335x-boneblue

BeagleBone Blue is robotics-oriented version of the BeagleBone Black (BBB).

This board can be indentified by the BLAx value after A335BNLT (BBB)
in the at24 eeprom:
BLAx [aa 55 33 ee 41 33 33 35  42 4e 4c 54 42 4c 41 30 |.U3.A335BNLTBLA2|]

http://beagleboard.org/blue
https://github.com/beagleboard/beaglebone-blue

firmware: https://github.com/beagleboard/beaglebone-black-wireless/tree/master/firmware
wl18xx mac address: /proc/device-tree/ocp/ethernet@4a100000/slave@4a100200/mac-address

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
CC: Jason Kridner <jkridner@beagleboard.org>
CC: Drew Fustini <drew@beagleboard.org>
Acked-by: Jason Kridner <jkridner@beagleboard.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>