providers/mlx5: Fix warning: 'prev' may be used uninitialized

This patch addresses a compiler warning indicating that the 'prev'
variable may be used uninitialized in the function
dr_vports_table_del_wire. Although this warning is a false positive,
it is important to resolve it to prevent potential confusion and
maintain code quality.

The 'while (vport)' loop is intended to start from the second element
of the linked list, as the first element is already checked by a
preceding condition. By initializing 'prev' to the first element
and 'vport' to 'prev->next', we ensure that the loop logic remains
correct and the warning is eliminated.

This change does not alter the functionality of the code but enhances
its clarity and robustness by ensuring all variables are properly
initialized before use.

Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>

providers/mlx5/dr_vports.c

@@ -241,7 +241,8 @@ void dr_vports_table_del_wire(struct dr_devx_vports *vports)
 		goto out_unlock;
 	}
 
-	vport = h->buckets[idx];
+	prev = h->buckets[idx];
+	vport = prev->next;
 	while (vport) {
 		if (vport == wire) {
 			prev->next = vport->next;