bridge: return boolean instead of integer in br_multicast_is_router
Return statements in functions returning bool should use
true/false instead of 1/0.
This issue was detected with the help of Coccinelle.
Fixes: 8316e5715542 ("bridge: Fix build error when IGMP_SNOOPING is not enabled") Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Reviewed-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>