tree-wide: Mark some constants as unsigned

All these are really unsigned and used as such. This silences some
-Wformat-signedness warnings with gcc.

src/network/netdev/bridge.h

@@ -4,8 +4,8 @@
 #include "conf-parser.h"
 #include "netdev.h"
 
-#define LINK_BRIDGE_PORT_PRIORITY_INVALID 128
-#define LINK_BRIDGE_PORT_PRIORITY_MAX 63
+#define LINK_BRIDGE_PORT_PRIORITY_INVALID 128U
+#define LINK_BRIDGE_PORT_PRIORITY_MAX 63U
 
 typedef struct Bridge {
         NetDev meta;

src/network/networkd-network.c

@@ -45,7 +45,7 @@
 #include "util.h"
 
 /* Let's assume that anything above this number is a user misconfiguration. */
-#define MAX_NTP_SERVERS 128
+#define MAX_NTP_SERVERS 128U
 
 static int network_resolve_netdev_one(Network *network, const char *name, NetDevKind kind, NetDev **ret) {
         const char *kind_string;