Enable unlocking (erasing/writing) W39V040FB chips

Add code for the unlocking (erasing/writing) of Winbond W39V040FB
chips, enabling erasing/writing this type of chip.

Corresponding to flashrom svn r1248.

Signed-off-by: Idwer Vollering <vidwer@gmail.com>
Acked-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
diff --git a/chipdrivers.h b/chipdrivers.h
index a65cb99..a6faf9f 100644
--- a/chipdrivers.h
+++ b/chipdrivers.h
@@ -119,6 +119,7 @@
 int printlock_w39v080a(struct flashchip *flash);
 int printlock_w39v080fa(struct flashchip *flash);
 int printlock_w39v080fa_dual(struct flashchip *flash);
+int unlock_w39v040fb(struct flashchip *flash);
 int unlock_w39v080fa(struct flashchip *flash);
 
 /* w29ee011.c */