mptcp: fix typos in comments

This patch fixes the spelling mistakes in comments.
The changes were generated using codespell and reviewed manually.

eariler -> earlier
greceful -> graceful

Signed-off-by: Shi-Sheng Yang <fourcolor4c@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240502154740.249839-1-fourcolor4c@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>