drm: Remove two-level menu in Kconfig

The Direct Rendering Manager Kconfig option is already a separate menu,
so remove the extra level to make it easier to navigate.
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/video/Kconfig

@@ -22,9 +22,7 @@ source "drivers/gpu/vga/Kconfig"
 source "drivers/gpu/host1x/Kconfig"
 source "drivers/gpu/ipu-v3/Kconfig"
 
-menu "Direct Rendering Manager"
 source "drivers/gpu/drm/Kconfig"
-endmenu
 
 menu "Frame buffer Devices"
 source "drivers/video/fbdev/Kconfig"