net: neterion: Fix wrong function name in comments

Fixes the following W=1 kernel build warning(s):

 drivers/net/ethernet/neterion/s2io.c:2759: warning: expecting prototype for s2io_poll(). Prototype was for s2io_poll_msix() instead
 drivers/net/ethernet/neterion/s2io.c:5304: warning: expecting prototype for s2io_ethtol_get_link_ksettings(). Prototype was for s2io_ethtool_get_link_ksettings() instead

Cc: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Yang Shen <shenyang39@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>