drm: Make FB_CORE to be selected if DRM fbdev emulation is enabled

Now that fbdev core has been split in FB_CORE and FB, make the DRM symbol
to select the FB_CORE option if the DRM fbdev emulation layer is enabled.

This allows to disable the CONFIG_FB option if is not needed, which will
avoid the need to explicitly disable each of the legacy fbdev drivers.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Helge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230719081544.741051-5-javierm@redhat.com

drivers/gpu/drm/Kconfig

@@ -9,6 +9,9 @@ menuconfig DRM
 	tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
 	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
 	select DRM_PANEL_ORIENTATION_QUIRKS
+	select DRM_KMS_HELPER if DRM_FBDEV_EMULATION
+	select FB_CORE if DRM_FBDEV_EMULATION
+	select FB_SYS_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
 	select HDMI
 	select I2C
 	select DMA_SHARED_BUFFER
@@ -96,7 +99,6 @@ config DRM_KUNIT_TEST
 config DRM_KMS_HELPER
 	tristate
 	depends on DRM
-	select FB_SYS_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
 	help
 	  CRTC helpers for KMS drivers.
 
@@ -132,8 +134,7 @@ config DRM_DEBUG_MODESET_LOCK
 
 config DRM_FBDEV_EMULATION
 	bool "Enable legacy fbdev support for your modesetting driver"
-	depends on DRM_KMS_HELPER
-	depends on FB=y || FB=DRM_KMS_HELPER
+	depends on DRM
 	select FRAMEBUFFER_CONSOLE if !EXPERT
 	select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY if FRAMEBUFFER_CONSOLE
 	default y