ChromeOS: Remove oprom_is_loaded

A global flag oprom_is_loaded was used to indicate to
U-boot that VGA option ROM was loaded and run, or that
native VGA init was completed on GMA device.

Implement this feature without dependency to CHROMEOS option
and replace use of global variable oprom_is_loaded with call
to gfx_get_init_done().

Change-Id: I7e1afd752f18e5346dabdee62e4f7ea08ada5faf
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/4309
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/include/bootmode.h b/src/include/bootmode.h
index d64bf93..a2c3411 100644
--- a/src/include/bootmode.h
+++ b/src/include/bootmode.h
@@ -23,6 +23,9 @@
 int get_developer_mode_switch(void);
 int get_recovery_mode_switch(void);
 
+int gfx_get_init_done(void);
+void gfx_set_init_done(int done);
+
 #if CONFIG_BOOTMODE_STRAPS
 int developer_mode_enabled(void);
 int recovery_mode_enabled(void);