src/: Use DAY_TO_STR() instead of its pattern

Cc: Tobias Stoeckmann <tobias@stoeckmann.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

src/usermod.c

@@ -586,8 +586,9 @@ static void new_spent (struct spwd *spent)
 	if (eflg) {
 		/* log dates rather than numbers of days. */
 		char new_exp[16], old_exp[16];
-		date_to_str (sizeof(new_exp), new_exp, user_newexpire * DAY);
-		date_to_str (sizeof(old_exp), old_exp, user_expire * DAY);
+
+		DAY_TO_STR(new_exp, user_newexpire);
+		DAY_TO_STR(old_exp, user_expire);
 #ifdef WITH_AUDIT
 		audit_logger (AUDIT_USER_CHAUTHTOK, Prog,
 		              "changing expiration date",