rsa: add support of padding pss

We add the support of the padding pss for rsa signature.
This new padding is often recommended instead of pkcs-1.5.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/image.h b/include/image.h
index e75d176..83a2d41 100644
--- a/include/image.h
+++ b/include/image.h
@@ -30,6 +30,7 @@
 #define IMAGE_ENABLE_FIT	1
 #define IMAGE_ENABLE_OF_LIBFDT	1
 #define CONFIG_FIT_VERBOSE	1 /* enable fit_format_{error,warning}() */
+#define CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT 1
 #define CONFIG_FIT_ENABLE_SHA256_SUPPORT
 #define CONFIG_SHA1
 #define CONFIG_SHA256