i40e: make use of i40e_vc_disable_vf

Replace i40e_vc_notify_vf_reset and i40e_reset_vf with a call to
i40e_vc_disable_vf which does this exact thing. This matches similar
code patterns throughout the driver.

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>