ht code.

The uninitialised pmu_backlight_lock causes the current Fedora test kernel
(which has spinlock debugging enabled) to panic on suspend.

This is suboptimal, so I fixed it.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>