ixgbe: Removing the unused PAGE_USE_COUNT() macro.

Removing the unused PAGE_USE_COUNT() macro. Also removing the unused
pages variable at ixgbe_configure_rx() function.

Signed-off-by: Breno Leitão <leitao@linux.vnet.ibm.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>