net: b44: use true,false for bool variables

This addresses the following coccinelle warning:

drivers/net/ethernet/broadcom/b44.c:2213:6-20: WARNING: Assignment of
0/1 to bool variable
drivers/net/ethernet/broadcom/b44.c:2218:2-16: WARNING: Assignment of
0/1 to bool variable
drivers/net/ethernet/broadcom/b44.c:2226:3-17: WARNING: Assignment of
0/1 to bool variable
drivers/net/ethernet/broadcom/b44.c:2230:3-17: WARNING: Assignment of
0/1 to bool variable

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>