arm: imx6q: pcm058: Convert pcm058 to use DM with DTs

Convert pcm058 support to use device trees and the driver model.
Add rudimentary boot scripts to the environment, expand README.

Signed-off-by: Niel Fourie <lusus@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
7 files changed