Add support for ST M25PX16 and mark it as supported

Tests were performed with write and verify operations to 4 different
M25PX16 chips with a Dediprog SF100.

Corresponding to flashrom svn r1270.

Signed-off-by: Carl Worth <carl.d.worth@intel.com>
Acked-by: Idwer Vollering <vidwer@gmail.com>
diff --git a/flashchips.h b/flashchips.h
index 3bfbf07..1c5e841 100644
--- a/flashchips.h
+++ b/flashchips.h
@@ -533,6 +533,7 @@
 #define ST_M25P32		0x2016
 #define ST_M25P64		0x2017
 #define ST_M25P128		0x2018
+#define ST_M25PX16		0x7115
 #define ST_M25PX32		0x7116
 #define ST_M25PX64		0x7117
 #define ST_M25PE10		0x8011