net: ethernet: nb8800: fix error handling of nb8800_probe()

In ops->reset() error handling case, clk_disable_unprepare() is missed
before return from this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: David S. Miller <davem@davemloft.net>