ixgbe: move num_vfs_macvlans allocation into separate function

ixgbe: move num_vfs_macvlans allocation into separate function

Move the code allocating memory for list of MAC addresses that
the VFs can use for MACVLAN into its own function.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26242766
(cherry picked from commit 2bc0972988c770dce093584ffd641856e3b18c5c)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>