lib/edid: Split out fill_lb_framebuffer()

Place it into new edid_fill_fb.c, and invert the logic of the Kconfig
guard (NATIVE_VGA_INIT_USE_EDID is now !NO_EDID_FILL_FB). It has to be
selected by all drivers that use MAINBOARD_DO_NATIVE_VGA_INIT but pro-
vide their own fill_lb_framebuffer() implementation.

Change-Id: I90634b835bd8e2d150b1c714328a5b2774d891bd
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/19764
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/drivers/xgi/common/Kconfig

@@ -1,3 +1,4 @@
 config DRIVERS_XGI_Z79_COMMON
 	bool
 	select VGA
+	select NO_EDID_FILL_FB

src/drivers/xgi/z9s/z9s.c

@@ -16,7 +16,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <arch/io.h>
-#include <edid.h>
 
 #include <console/console.h>
 #include <device/device.h>