MFD: ucb1x00-core: scan drivers in same order they're registered

Cosmetic patch to scan the list of drivers in the order that the drivers
are registered, rather than the reverse order.  This avoids surprises
when drivers get probed in the reverse order, and input devices get
registered in a different order due to bind/unbind than from boot.

Acked-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>