i40e/i40evf: Fix an accidental error with BIT_ULL replacement

A mask value of 0x1FF was accidentally replaced with a bit mask
causing flow director sideband to be broken.

Change-ID: Id3387f67dd1b567b41692b570b383c58671e1eae
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>