PR #189 from dmipx: d4xx: hwmc return success on ioctl

(cherry picked from commit cf7fe64)

Author: Nir-Az

kernel/realsense/d4xx.c

@@ -2534,8 +2534,10 @@ static int ds5_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
 			u16 dataLen = 0;
 			u16 bufLen = ctrl->dims[0];
 			ret = ds5_get_hwmc(state, data,	bufLen, &dataLen);
-			if (ret)
+			if (ret) {
+				ret = 0; // LRS doesn't expect to get errors with HWMC
 				break;
+			}
 			/* This is needed for librealsense, to align there code with UVC,
 		 	 * last word is length - 4 bytes header length */
 			dataLen -= 4;