tty: sysrq: switch the rest of keys to u8

Propagate u8 more from the bottom to the interface, so that sysrq
callers (usually drivers) see that u8 is expected.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230712081811.29004-4-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>