net: cosa: use BIT macro

This patch uses the BIT macro for setting individual bits,
to fix the following checkpatch.pl issue:
CHECK: Prefer using the BIT macro.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>