uboot-imx

cros_ec: Add a function for reading a flash map entry

A flash map describes the layout of flash memory in terms of offsets and
sizes for each region. Add a function to read a flash map entry from the
device tree.

Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>