tty: Make sysctl table const

tty: Make sysctl table const

Since commit 7abc9b53bd51 ("sysctl: allow registration of const struct
ctl_table"), the sysctl registration API allows for struct ctl_table to be
in read-only memory. Move tty_table to be declared at build time, instead
of having to be dynamically allocated at boot time.

Cc: Thomas Weißschuh <linux@weissschuh.net>
Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Ricardo B. Marliere <rbm@suse.com>
Link: https://lore.kernel.org/r/20241213-sysctl_const-tty-v1-1-2e2bcec77f85@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>