input: i8042: Convert to use the input library

At present the i8042 driver has its own logic and keymaps. In an effort to
unify the code, move it over to use the input library. This changes most of
the keycode-processing logic since it is now in that library. The main
responsibilities of the driver are now to handle the LEDs, deal with the
PS/2 extended keycodes and initialise the the keyboard.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>