arm: convert pcm037 platform to use smsc911x

Updated to also specify SMSC911X_FORCE_INTERNAL_PHY, as the external phy
detection hardware strap is incorrectly pulled high on this platform.

Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>