OMAP3: Add SMSC9221 device tree for omap devices connected on GPMC.

Some OMAP3 devices support an SMSC ethernet PHY connected to the GPMC bus.
This copies this device tree from Linux 4.9.y stable

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>