drivers/net/ixgbe: fix sparse warning: Should it be static?

Impact: Make symbol static.

Fix this sparse warning:
  drivers/net/ixgbe/ixgbe_82598.c:59:5: warning: symbol 'ixgbe_get_pcie_msix_count_82598' was not declared. Should it be static?

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>