lib/boot_device: Add API for write protect a region

Add API that should be implemented by the boot media drivers
for write-protecting a subregion.

Change-Id: I4c9376e2c2c7a4852f13c65824c6cd64a1c6ac0a
Signed-off-by: Rizwan Qureshi <rizwan.qureshi@intel.com>
Reviewed-on: https://review.coreboot.org/c/28724
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/lib/boot_device.c

@@ -20,6 +20,13 @@ void __weak boot_device_init(void)
 	/* Provide weak do-nothing init. */
 }
 
+int __weak boot_device_wp_region(struct region_device *rd,
+				 const enum bootdev_prot_type type)
+{
+	/* return a failure, make aware WP is not implemented */
+	return -1;
+}
+
 static int boot_device_subregion(const struct region *sub,
 				struct region_device *subrd,
 				const struct region_device *parent)