m68k: mcfgpio: Fix incorrect register offset for CONFIG_M5441x

Fix a typo in the CONFIG_M5441x preprocessor condition, where the GPIO
register offset was incorrectly set to 8 instead of 0. This prevented
proper GPIO configuration for m5441x targets.

Fixes: bea8bcb1 ("m68knommu: Add support for the Coldfire m5441x.")
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
Signed-off-by: Greg Ungerer <gerg@kernel.org>