msm: mdss: Add missing BL lock around BL-related info

The bl_updated variable requires the BL lock. Otherwise, it can be
corrupted and cause backlight issues.

Change-Id: I55eb4b8d525765ede4f27a404f5c3f1f0b446719
Signed-off-by: Benet Clark <benetc@codeaurora.org>

Conflicts:

	drivers/video/msm/mdss/mdss_mdp_splash_logo.c

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>