net/mlx5: Fix uninitialized variable warning

Add variable initialization to eliminate the warning
"variable may be used uninitialized".

Fixes: 5f29458b ("net/mlx5e: Support dump callback in TX reporter")
Signed-off-by: Moshe Tal <moshet@mellanox.com>
Reviewed-by: Aya Levin <ayal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/health.c

@@ -242,8 +242,8 @@ static int mlx5e_health_rsc_fmsg_binary(struct devlink_fmsg *fmsg,
 
 {
 	u32 data_size;
+	int err = 0;
 	u32 offset;
-	int err;
 
 	for (offset = 0; offset < value_len; offset += data_size) {
 		data_size = value_len - offset;