ixgbe: Fix set_ringparam in ixgbe to use the same memory pools.

The adapter rings are kcalloc()'d, but in set_ringparam() in ixgbe_ethtool,
we replace that memory from the vmalloc() pool.  This can result in a NULL
pointer reference when trying to modify the rings at a later time, or on
device removal.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>