hwdb: Add Huawei section and remap keys (#11406)

hwdb: Add support for 'Huawei WMI hotkeys' driver

Since 'Huawei WMI hotkeys' driver finally got merged into kernel
[commit](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/huawei-wmi.c?id=bf4fb28c6e74495de9e1e4ad359cd2272ac12c53),
this remaps 'KEY_MICMUTE' to 'F20' to make the key work and disables
brightness keys on (MACH-WX9) since it's already supported by kernel.