Add parsing of Xiaomi devices

[vbatoufflet]

This PR makes it that the device parsing for Xiaomi devices stop returning:

Family: "Generic Smartphone"
Brand:  "Generic"
Model:  "Smartphone"

but instead:

Family: "Xiaomi 23053RN02A"
Brand:  "Xiaomi"
Model:  "23053RN02A"

[dgoldstein0]

This is the wrong repo to make the change to. uaparser/yaml.go is generated by https://github.com/ua-parser/uap-go/blob/master/build.sh from our submodule of ua-parser/uap-core. All regex changes ought to be first reviewed and merged into that repository. If you go that route, I'd be happy to accept a submodule update of uap-core to pull in any changes you contribute there.

[vbatoufflet]

My bad, didn't catch that. Just created a new PR towards the proper repository ua-parser/uap-core#639