flashchips: Add IS25LP256 and IS25WP256

Tested IS25LP256 using Raspberry Pi and Dediprog SF600 programmers.
Tested IS25WP256 using Dediprog SF600.

Change-Id: Idf7a224abcde5f7935d9ef88309f78207de60a7a
Signed-off-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-on: https://review.coreboot.org/29306
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/flashchips.h b/flashchips.h
index 429acef..434c355 100644
--- a/flashchips.h
+++ b/flashchips.h
@@ -456,9 +456,11 @@
 #define ISSI_ID_SPI		0x9D	/* ISSI ID used for SPI flash, see also PMC_ID_NOPREFIX */
 #define ISSI_IS25LP064		0x6017
 #define ISSI_IS25LP128		0x6018
+#define ISSI_IS25LP256		0x6019
 #define ISSI_IS25WP032		0x7016
 #define ISSI_IS25WP064		0x7017
 #define ISSI_IS25WP128		0x7018
+#define ISSI_IS25WP256		0x7019
 #define ISSI_PMC_IS29GL032B	0xF9
 #define ISSI_PMC_IS29GL032T	0xF6
 #define ISSI_PMC_IS29GL064B	0x7E1000