Declare get_write_protect_state() without ChromeOS

Change-Id: I72471ac68088cd26f8277b27b75b7d44ad72cfc4
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5642
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/vendorcode/google/chromeos/chromeos.h

@@ -24,9 +24,6 @@
 #include <stdint.h>
 #include <bootmode.h>
 
-/* functions implemented per mainboard: */
-int get_write_protect_state(void);
-
 /* functions implemented in vbnv.c: */
 int get_recovery_mode_from_vbnv(void);
 int vboot_wants_oprom(void);