drivers/net/atlx: fix sparse warnings: make symbols static

Fix this sparse warnings:

  drivers/net/atlx/atl1.c:198:16: warning: symbol 'atl1_check_options' was not declared. Should it be static?
  drivers/net/atlx/atl1.c:526:5: warning: symbol 'atl1_read_mac_addr' was not declared. Should it be static?

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>