misc: Deal with smatch warnings about the bitfields

Use unsigned ints for the bitfield.
diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index bddf046..781e43a 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -521,10 +521,10 @@
 		} hsl;
 		struct {
 			uint8_t bts_type;
-			int configured:1,
-			    skip_reset:1,
-			    did_reset:1,
-			    wait_reset:1;
+			unsigned int configured:1,
+				skip_reset:1,
+				did_reset:1,
+				wait_reset:1;
 			struct osmo_timer_list reset_timer;
 		} nokia;
 	};