flashchips: Add XMC XM25RH256C

There is no public datasheet available. However, given that all the
512C variants are almost identical,  we're going to assume the same
for the RH256C. That is, a QH256C plus RPMC features. Its device id
has been confirmed by Priyo on the flashprog mailing list.

Change-Id: Ie4c5a3102a0ba00b5e5683988959df17cbc5c1b7
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/576
diff --git a/include/flashchips.h b/include/flashchips.h
index b73de30..7654c33 100644
--- a/include/flashchips.h
+++ b/include/flashchips.h
@@ -877,6 +877,7 @@
 #define XMC_XM25QU128C		0x4118
 #define XMC_XM25QU256C		0x4119
 #define XMC_XM25QU512C		0x4120
+#define XMC_XM25RH256C		0x4319
 #define XMC_XM25RH512C		0x4320
 #define ST_M25PX80		0x7114
 #define ST_M25PX16		0x7115