Several device trees use something like:

	stdout-path = "serial0:115200n8";

Currently of_device_is_stdout_path fails to do the right thing here
because it expects an absolute node path and no options. So split off
options (everything after the colon) and resolve aliases.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>