selftests: tcp_ao: fix spelling in seq-ext.c comment

Spelling fix:
conneciton --> connection

This is a non-functional change aimed at improving code clarity.

Signed-off-by: Ankit Chauhan <ankitchauhan2065@gmail.com>
Link: https://patch.msgid.link/20250610071903.67180-1-ankitchauhan2065@gmail.com


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