arch: xtensa: defconfig: Drop obsolete CONFIG_NET_CLS_TCINDEX

This option was removed from the Kconfig in commit
8c710f75 ("net/sched: Retire tcindex classifier") but it was not
removed from the defconfigs.

Fixes: 8c710f75 ("net/sched: Retire tcindex classifier")
Signed-off-by: Johan Korsnes <johan.korsnes@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20250323191004.112743-1-johan.korsnes@gmail.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>