hw/net/can: Make CanBusClientInfo::can_receive() return a boolean

The CanBusClientInfo::can_receive handler return whether the
device can or can not receive new frames. Make it obvious by
returning a boolean type.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>

include/net/can_emu.h

@@ -83,7 +83,7 @@ typedef struct CanBusClientState CanBusClientState;
 typedef struct CanBusState CanBusState;
 
 typedef struct CanBusClientInfo {
-    int (*can_receive)(CanBusClientState *);
+    bool (*can_receive)(CanBusClientState *);
     ssize_t (*receive)(CanBusClientState *,
         const struct qemu_can_frame *frames, size_t frames_cnt);
 } CanBusClientInfo;