net: aquantia: Make function aq_fw1x_set_power() static

Fixes the following sparse warning:

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_utils.c:873:5: warning:
 symbol 'aq_fw1x_set_power' was not declared. Should it be static?

Fixes: a0da96c0

 ("net: aquantia: implement WOL support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>