video-uclass: Fix logical-not-parentheses warning

With clang-4.0 and later we see:
warning: logical not is only applied to the left hand side of this bitwise
operator [-Wlogical-not-parentheses]
        if ((!gd->flags & GD_FLG_RELOC))
             ^          ~

And while the compiler suggests adding parenthesis around gd->flags, a
reading of the code says that we want to know when GD_FLG_RELOC is not
set and then return.

Cc: Simon Glass <sjg@chromium.org>
Cc: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>

drivers/video/video-uclass.c

@@ -272,7 +272,7 @@ static int video_post_bind(struct udevice *dev)
 	ulong size;
 
 	/* Before relocation there is nothing to do here */
-	if ((!gd->flags & GD_FLG_RELOC))
+	if (!(gd->flags & GD_FLG_RELOC))
 		return 0;
 	size = alloc_fb(dev, &addr);
 	if (addr < gd->video_bottom) {