Disabling the clocks is a standard procedure while stopping the
device. On family 8000 however, disabling the bus master DMA clock
increases the NIC's power consumption.

To fix this, skip this call if the device family is
IWL_DEVICE_FAMILY_8000.
Signed-off-by: NAvri Altman <avri.altman@intel.com>
Reviewed-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>