net: ns83820: code cleanup for ns83820_probe_phy()

This patch is to do code cleanup for ns83820_probe_phy().
It deletes unused variable 'first', commented out code,
and the pointless 'for' loop.

Signed-off-by: Mao Wenan <maowenan@huawei.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>