mptcp: token: fix unititialized variable

gcc complains about use of uninitialized 'num'. Fix it by doing the first
assignment of 'num' when the variable is declared.

Fixes: 96d890daad05 ("mptcp: add msk interations helper")
Signed-off-by: Davide Caratti <[e-mail]>
Acked-by: Paolo Abeni <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/mptcp/token.c

···
 {
 	struct mptcp_sock *ret = NULL;
 	struct hlist_nulls_node *pos;
-	int slot, num;
+	int slot, num = 0;
 
 	for (slot = *s_slot; slot <= token_mask; *s_num = 0, slot++) {
 		struct token_bucket *bucket = &token_hash[slot];