move ClientSlot_t from fsm to client

this allows to reuse the client slot information in as client for
other rspro_utils methods
diff --git a/src/client.h b/src/client.h
index b4e4672..b772a20 100644
--- a/src/client.h
+++ b/src/client.h
@@ -42,6 +42,9 @@
 	uint16_t bankd_port;
 	struct ipa_client_conn *bankd_conn;
 	struct osmo_fsm_inst *bankd_fi;
+
+	/* client id and slot number */
+	ClientSlot_t *clslot;
 };
 
 void ipa_client_conn_send_rspro(struct ipa_client_conn *ipa, RsproPDU_t *rspro);