net: ethernet: aquantia: Fix wrong return value

In function hw_atl_a0_hw_multicast_list_set(), when an invalid
request is encountered, a negative error code should be returned.

Fixes: bab6de8f

 ("net: ethernet: aquantia: Atlantic A0 and B0 specific functions")
Cc: David VomLehn <vomlehn@texas.net>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>