Input: olpc_apsp - enable the SP clock

Without the clock, the keyboard controller won't operate.
Tested on an OLPC XO 1.75.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>