ARM: OMAP: Fix OMAP1 compilation after MPUIO check change

The recent MPUIO range change fix breaks compilation if
CONFIG_ARCH_OMAP24XX isn't defined; it should be OMAP_MAX_GPIO_LINES not
MAX_GPIO_LINES I believe. This one liner fixes it.

Signed-off-by: Jonathan McDowell <noodles@earth.li>
Signed-off-by: Tony Lindgren <tony@atomide.com>