Generalise the Corgi backlight driver by moving the default intensity and
limit mask settings into the platform specific data structure.  This enables
the driver to support other Zaurus hardware, specifically the SL-6000x (Tosa)
model.

Also change the spinlock to a mutex (the spinlock is overkill).
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>