iavf: Fix return of set the new channel count

Fixed return correct code from set the new channel count.
Implemented by check if reset is done in appropriate time.
This solution give a extra time to pf for reset vf in case
when user want set new channel count for all vfs.
Without this patch it is possible to return misleading output
code to user and vf reset not to be correctly performed by pf.

Fixes: 5520deb1

 ("iavf: Enable support for up to 16 queues")
Signed-off-by: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>