video: exynos_mipi_dsi: Unlock the mutex before returning

Mutex should be unlocked before returning. Fixes mutex lock-unlock
imbalance issue.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/exynos/exynos_mipi_dsi_common.c

@@ -376,6 +376,7 @@ int exynos_mipi_dsi_rd_data(struct mipi_dsim_device *dsim, unsigned int data_id,
 			"data id %x is not supported current DSI spec.\n",
 			data_id);
 
+		mutex_unlock(&dsim->lock);
 		return -EINVAL;
 	}