ARM: OMAP3LOGIC: Add generic smsc911x support when connected to GPMC

Introduce of a generic way to setup smsc911x based Ethernet
controller connected to GPMC similar to gpmc-smc91x but without
timing setup.

Signed-off-by: Tim Nordell <tim.nordell@logicpd.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>