ANDROID: GKI: restore termiox fields

To keep the kernel abi stable at this point in time, restore the termiox
pointer in struct tty_struct and the set_termiox() callback in struct
tty_operations that were removed in eef2158b ("tty: Remove dead
termiox code")

Bug: 161946584
Fixes: eef2158b ("tty: Remove dead termiox code")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Iea4739fc4725b6ebd10fc5e0367f91d938b6e364