rsa: use pkcs11 uri as defined in rfc7512

pkcs11 : change engine uri to use full pk11-URI as defined in:

https://www.rfc-editor.org/rfc/rfc7512.html
Signed-off-by: Ayoub Zaki <ayoub.zaki@embetrix.com>
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index d20bdb5..7ae163f 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -116,15 +116,15 @@
 		if (keydir)
 			if (strstr(keydir, "object="))
 				snprintf(key_id, sizeof(key_id),
-					 "pkcs11:%s;type=public",
+					 "%s;type=public",
 					 keydir);
 			else
 				snprintf(key_id, sizeof(key_id),
-					 "pkcs11:%s;object=%s;type=public",
+					 "%s;object=%s;type=public",
 					 keydir, name);
 		else
 			snprintf(key_id, sizeof(key_id),
-				 "pkcs11:object=%s;type=public",
+				 "object=%s;type=public",
 				 name);
 	} else if (engine_id) {
 		if (keydir)
@@ -238,15 +238,15 @@
 		if (keydir)
 			if (strstr(keydir, "object="))
 				snprintf(key_id, sizeof(key_id),
-					 "pkcs11:%s;type=private",
+					 "%s;type=private",
 					 keydir);
 			else
 				snprintf(key_id, sizeof(key_id),
-					 "pkcs11:%s;object=%s;type=private",
+					 "%s;object=%s;type=private",
 					 keydir, name);
 		else
 			snprintf(key_id, sizeof(key_id),
-				 "pkcs11:object=%s;type=private",
+				 "object=%s;type=private",
 				 name);
 	} else if (engine_id) {
 		if (keydir && name)