drm/i915: Fix calculation of backlight value in combined mode
commit
ba3820ade317ee36e496b9b40d2ec3987dd4aef0 upstream.
[The upstream commit above is a combination of revert + one-liner fix.
This patch contains only the latter that is needed for 2.6.37.x.]
This patch fixes the backlight level calculation for combination mode
used in some models like GM45. It's due to a wrong bit shift
introduced by the commit
a95735569312f2ab0c80425e2cd1e5cb0b4e1870
drm/i915: Refactor panel backlight controls
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=23472
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34524
Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=672946
Signed-off-by: Takashi Iwai <tiwai@suse.de>