mctpd: zero initialize link data

On non-bus-owner modes, link->slot_busowner will be uninitialized,
leading to segmentation fault when running sd_bus_slot_unref.

    ==3850684== Conditional jump or move depends on uninitialised value(s)
    ==3850684==    at 0x48FB448: sd_bus_slot_unref (in /usr/lib/aarch64-linux-gnu/libsystemd.so.0.38.0)
    ==3850684==    by 0x1123E3: free_link (mctpd.c:3263)
    ==3850684==    by 0x1125CB: free_links (mctpd.c:3308)
    ==3850684==    by 0x113D63: main (mctpd.c:3900)

Simply zero initialize the link data.

Signed-off-by: Khang D Nguyen <[email protected]>

Author: khangng-ampere

src/mctpd.c

@@ -3573,7 +3573,7 @@ static int add_interface(struct ctx *ctx, int ifindex)
 		return -ENOENT;
 	}
 
-	struct link *link = malloc(sizeof(*link));
+	struct link *link = calloc(sizeof(*link), 1);
 	if (!link)
 		return -ENOMEM;