GPU-DRM-Exynos: Delete an unnecessary check before the function call "vunmap"

The vunmap() function performs also input parameter validation.
Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NSean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/a5a79711-10a3-e304-a897-892ebdf2ff9f@users.sourceforge.net

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -269,7 +269,6 @@ static void exynos_drm_fbdev_destroy(struct drm_device *dev,
 	struct exynos_drm_gem *exynos_gem = exynos_fbd->exynos_gem;
 	struct drm_framebuffer *fb;
 
-	if (exynos_gem->kvaddr)
 	vunmap(exynos_gem->kvaddr);
 
 	/* release drm framebuffer and real buffer */