config: am335x_evm: detect BeagleBone Blue using BLA

config: am335x_evm: detect BeagleBone Blue using BLA

BeagleBone Blue is next grenation of boards from BeagleBoard.org, focusing
on robotics with a TI wl1835 wireless module for connectivity.

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: Tom Rini <trini@konsulko.com>
CC: Jason Kridner <jkridner@beagleboard.org>
CC: Will Newton <willn@resin.io>
Reviewed-by: Tom Rini <trini@konsulko.com>