HID: Add Mapping for System Microphone Mute

HUTRR110 added a new usage code for a key that is supposed to
mute/unmute microphone system-wide.

Map the new usage code(0x01 0xa9) to keycode KEY_MICMUTE.
Additionally hid-debug is adjusted to recognize this keycode as well.

Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>