Input: olpc_apsp - depend on ARCH_MMP

The OLPC XO-1.75 and XO-4 are ARM-based laptops, using the Marvell
MMP architecture, so don't present this driver on other architectures
except for build-testing purposes.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>