netdev: smc91x: drop Blackfin cruft

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

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>