arm: convert omap ldp platform to use smsc911x

from 2.6.29, smc911x isn't maintained anymore. A new driver, smsc911x,
will replace it. so convert omap_ldp to use smsc911x driver.

Signed-off-by: Stanley.Miao <stanley.miao@windriver.com>
Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>