smc911x: check if the device is ready before using it
poll the READY bit in PMT_CTRL. Any other access to the device is
forbidden while this bit isn't set. Try for 100ms
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>