m68k/gpio: remove arch specific sysfs bus device

The ColdFire architecture specific gpio support code registers a sysfs
bus device named "gpio". This clashes with the new generic API device
added in commit 3c702e99 ("gpio: add a userspace chardev ABI for GPIOs").

The old ColdFire sysfs gpio device was never used for anything specific,
and no links or other nodes were created under it. The new API sysfs gpio
device has all the same default sysfs links (device, drivers, etc) and
they are properly populated.

Remove the old ColdFire sysfs gpio registration.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>