msm_fb: display: fix primary not resuming after suspend when hdmi connected

Update bl_updated variable only after succesfully changing backlight,
otherwise it can be set on hdmi play which doesn't really update
backlight so primary remains blank.

Change-Id: Ia08713ff0fbc88a98acd004a909c995fcd5726c6
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>