mach-snapdragon: set serial number

In the typical case where we chainload from ABL, the serial number is
available in the DT bootargs. Read it out and set the serial#
environment variable so that it can be used by fastboot.

Change-Id: If3af14ef25e3d0b637f9b7e30218a95250f5f1c1
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
3 files changed