net: bridge: fdb: convert is_local to bitops

[ Upstream commit 6869c3b02b596eba931a754f56875d2e2ac612db ]

The patch adds a new fdb flags field in the hole between the two cache
lines and uses it to convert is_local to bitops.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: bee2ef946d31 ("net: bridge: br_fdb_external_learn_add(): always set EXT_LEARN")
Signed-off-by: Sasha Levin <sashal@kernel.org>