disp: msm: dsi: Fix deadlock issue in debugfs_esd_trigger_check function

In debugfs_esd_trigger_check, display mutex is not unlocked in error 
scenario which may lead to deadlock. This change adds fix to handle this.

Change-Id: I44d78959630a49bd1e9dcf871cfc108ac43232db
Signed-off-by: Srihitha Tangudu <tangudu@codeaurora.org>