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.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
1 file changed