omap3evm: MIgrate to smsc911x ethernet driver

Migrate to smsc911x ethernet driver instead of smc911x driver.
The smsc911x ethernet driver supports NAPI and performs better
under heavy traffic. With the smc911x driver we were witnessing
very high iowait time for high IO load over NFS.

Signed-off-by: Sriramakrishnan <srk@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>