drm/gma500: make fbdev support really optional

Currently enabling Intel GMA DRM support automatically pulls
in fbdev dependency. However this dep is unnecessary since
DRM core already handles this for us (DRM_FBDEV_EMULATION).
Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468586897-32298-11-git-send-email-tjakobi@math.uni-bielefeld.de

drivers/gpu/drm/gma500/Kconfig

 config DRM_GMA500
 	tristate "Intel GMA5/600 KMS Framebuffer"
 	depends on DRM && PCI && X86
-	select FB_CFB_COPYAREA
-	select FB_CFB_FILLRECT
-	select FB_CFB_IMAGEBLIT
 	select DRM_KMS_HELPER
-	select DRM_KMS_FB_HELPER
 	select DRM_TTM
 	# GMA500 depends on ACPI_VIDEO when ACPI is enabled, just like i915
 	select ACPI_VIDEO if ACPI