msm: camera: Fix null pointer exception in regulator disable

Adding a NULL check before disable regulator to make sure
that its not released before.

Change-Id: I21ff1649db3e00588f1c320418fca270bc0264bc
Signed-off-by: Vijay kumar Tumati <vtumati@codeaurora.org>

drivers/media/platform/msm/camera_v2/common/msm_camera_io_util.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2011-2014, The Linux Foundataion. All rights reserved.
+/* Copyright (c) 2011-2014, 2017, The Linux Foundataion. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -556,12 +556,16 @@ int msm_camera_enable_vreg(struct device *dev, struct camera_vreg_t *cam_vreg,
 					continue;
 			} else
 				j = i;
-			regulator_disable(reg_ptr[j]);
-			if (cam_vreg[j].delay > 20)
-				msleep(cam_vreg[j].delay);
-			else if (cam_vreg[j].delay)
-				usleep_range(cam_vreg[j].delay * 1000,
-					(cam_vreg[j].delay * 1000) + 1000);
+			if (reg_ptr[j]) {
+				regulator_disable(reg_ptr[j]);
+				if (cam_vreg[j].delay > 20)
+					msleep(cam_vreg[j].delay);
+				else if (cam_vreg[j].delay)
+					usleep_range(
+						cam_vreg[j].delay * 1000,
+						(cam_vreg[j].delay * 1000)
+						+ 1000);
+			}
 		}
 	}
 	return rc;