net: hns3: Fix return of uninitialized variable ret

In the unlikely event that rule_cnt is zero the variable ret is
not assigned a value and function hclge_dbg_dump_fd_tcam can end
up returning an unitialized value in ret. Fix this by explicitly
setting ret to zero before the for-loop.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: b5a0b70d ("net: hns3: refactor dump fd tcam of debugfs")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>