i40e: drop i40e_pf *pf from i40e_vc_disable_vf()

It's never used, and the vf structure could get back to the PF if
necessary. Lets just drop the extra unneeded parameter.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>