keymap: Add microphone mute keymap for Dell Latitude

On the Dell Latitude, the mic mute key event is generated by wmi
driver, the keycode assigned to this hotkey from kernel is
KEY_MICMUTE (248), this keycode is too big for xorg to handle,
in the xorg, the XF86AudioMicMute is assigned to F20.

Please refer to 4e648ea0 of xkeyboard-config.

BugLink: https://bugs.launchpad.net/bugs/1326684
BugLink: https://bugs.launchpad.net/bugs/1339998
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Martin Pitt <martin.pitt@ubuntu.com>
Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
keymap: Annotate all micmute workarounds

Add a comment to all assignments to f20 that this actually should be "micmute"
in a future when we aren't limited by X.org's key code limiations any more.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
hwdb: update

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
hwdb/ids-update.pl: bring up to date with upstream.

This includes pieces of the following commits:

    d060b62fcb4746d3758c567e9379c6728a035b66
    bd63a88fb0478da2e93c363849b73aed8be36ae7

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>