Merge branch 'mptcp-miscellaneous-cleanup'

Mat Martineau says:

====================
mptcp: Miscellaneous cleanup

Here are some cleanup patches we've collected in the MPTCP tree.

Patches 1-4 do some general tidying.

Patch 5 adds an explicit check at netlink command parsing time to
require a port number when the 'signal' flag is set, to catch the error
earlier.

Patches 6 & 7 fix up the MPTCP 'enabled' sysctl, enforcing it as a
boolean value, and ensuring that the !CONFIG_SYSCTL build still works
after the boolean change.
====================

Link: https://lore.kernel.org/r/20210527235430.183465-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>