ixgbe: remove unneeded fdir pb alloc case

The packet buffer is correctly allocated by generic pb allocation
path in ixgbe_configure() there is no need to do the allocation
here as well.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>