ARM: pxa: magician: Add missing regulator for PWM backlight

Add a fake regulator, which is required for the correct initialization
of the PWM backlight driver.

Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
[ added a missing include for fixed regulator ]
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>