ice: remove ice_mbx_deinit_snapshot

The ice_mbx_deinit_snapshot function's only remaining job is to clear the
previous snapshot data. This snapshot data is initialized when SR-IOV adds
VFs, so it is not necessary to clear this data when removing VFs. Since no
allocation occurs we no longer need to free anything and we can safely
remove this function.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Marek Szlosek <marek.szlosek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>