Merge branch 'mptcp-so_sndtimeo-and-misc-cleanup'

Mat Martineau says:

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mptcp: SO_SNDTIMEO and misc. cleanup

Patch 1 adds support for the SO_SNDTIMEO socket option on MPTCP sockets.

The remaining patches are various small cleanups:

Patch 2 removes an obsolete declaration.

Patches 3 and 5 remove unnecessary function parameters.

Patch 4 removes an extra cast.

Patches 6 and 7 add some const and ro_after_init modifiers.

Patch 8 removes extra storage of TCP helpers.
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Link: https://lore.kernel.org/r/20220216021130.171786-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>