platform/x86: dell-wmi: Add a keymap for KEY_MUTE in type 0x0010 table

Some platforms send the speaker-mute key from EC. dell-wmi can't
recognize it.

Add a new keymap for KEY_MUTE in type 0x0010 table.

Signed-off-by: Koba Ko <koba.ko@canonical.com>
Link: https://lore.kernel.org/r/20230117123436.200440-1-koba.ko@canonical.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>