ideapad_laptop: Fix for backlight regression

ideapad_laptop: Fix for backlight regression

[Paul Buonopane]

26bff5f099722fa7c38796a3ccd0e880cf1a524a introduced a regression in 
ideapad_laptop (https://bugzilla.kernel.org/show_bug.cgi?id=110021).  
I've created a quick fix as a pull request: 
https://github.com/torvalds/linux/pull/236  Here's the patch, for 
convenience:

*** drivers/platform/x86/ideapad-laptop.c.old    2015-12-27 
03:48:36.243613843 -0500
--- drivers/platform/x86/ideapad-laptop.c    2015-12-27 
03:49:28.310280733 -0500
*************** static int ideapad_acpi_add(struct platf
*** 933,939 ****
       ideapad_sync_rfk_state(priv);
       ideapad_sync_touchpad_state(priv);

!     if (acpi_video_get_backlight_type() == acpi_backlight_vendor) {
           ret = ideapad_backlight_init(priv);
           if (ret && ret != -ENODEV)
               goto backlight_failed;
--- 933,939 ----
       ideapad_sync_rfk_state(priv);
       ideapad_sync_touchpad_state(priv);

!     if (acpi_video_get_backlight_type() != acpi_backlight_vendor) {
           ret = ideapad_backlight_init(priv);
           if (ret && ret != -ENODEV)
               goto backlight_failed;

I've tested the patch on a Yoga 900 running 4.3.3 x86_64 with a few 
other compatibility patches.  Backlight controls work perfectly with it 
applied.