tty: tty_buffer: better types in __tty_buffer_request_room()

* use bool for 'change' as it holds a result of a boolean.
* use size_t for 'left', so it is the same as 'size' which it is
  compared to. Both are supposed to contain an unsigned value.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230816105530.3335-9-jirislaby@kernel.org


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