Instead of using unsigned char for the byte data switch to using u8. Also
use unsigned int for the command codes and timeouts, and have
ps2_handle_ack() and ps2_handle_response() return bool instead of int, as
they do not return error codes but rather signal whether a byte was handled
or not handled. ps2_is_keyboard_id() now returns bool as well.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>