nfp: fix schedule in atomic context when sync mc address

The callback `.ndo_set_rx_mode` is called in atomic context, sleep
is not allowed in the implementation. Now use workqueue mechanism
to avoid this issue.

Fixes: de624864

 ("nfp: add support for multicast filter")
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Reviewed-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20221220152100.1042774-1-simon.horman@corigine.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>