i40e: ensure reset occurs when disabling VF

It is possible although rare that we may not reset when
i40e_vc_disable_vf() is called. This can lead to some weird
circumstances with some values not being properly set. Modify
i40e_reset_vf() to return a code indicating whether it reset or not.

Now, i40e_vc_disable_vf() can wait until a reset actually occurs. If it
fails to free up within a reasonable time frame we'll display a warning
message.

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>