cifs: update new ACE pointer after populate_new_aces.

After the fix for retaining externally set ACEs with cifsacl and
modefromsid,idsfromsid, there was an issue in populating the
inherited ACEs after setting the ACEs introduced by these two modes.
Fixed this by updating the ACE pointer again after the call to
populate_new_aces.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Rohith Surabattula <rohiths@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>