[MTD] ixp2000: Remove port setting code

Setting the slowport to 8-bit mode is something that ought to be
done in the IXP2000 generic code, not in the MTD map driver.  See
the description for ARM patch 2493/1 for an explanation.

http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=2493/1

Now that 2493/1 has been accepted and will be upstream soon, this
doesn't need to be done in the map driver anymore.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>