octeontx2-af: Use GFP_ATOMIC under spin lock

The function nix_update_mce_list() is called from
nix_update_bcast_mce_list(), and a spin lock is held
here, so we should use GFP_ATOMIC instead.

Fixes: 4b05528e

 ("octeontx2-af: Update bcast list upon NIXLF alloc/free")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>