smc91x: remove OMAP specific bits

Now that all OMAP boards are using the board resources, we don't need
to keep the arch/board specific crap in the driver header.

Cc: linux-net@vger.kernel.org
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>