ice: move out debugfs init from fwlog

The root debugfs directory should be available from driver side, not
from library. Move it out from fwlog code.

Make similar to __fwlog_init() __fwlog_deinit() and deinit debugfs
there. In case of ice only fwlog is using debugfs.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Rinitha S <sx.rinitha@intel.com> (A Contingent worker at Intel)
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>