Input: libps2 - use u8 for byte data

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>