[css-ui-4] Remove type name in value declaration for compat-auto

[pyoor]

The compat-auto value definition shown in the following URL includes the name in the syntax field.

csswg-drafts/css-ui-4/Overview.bs

Line 1892 in a2f32c8

<pre class=prod style="white-space: normal"><<compat-auto>> = <dfn>searchfield</dfn> | <dfn>textarea</dfn> | <dfn>push-button</dfn> | <dfn>slider-horizontal</dfn> | <dfn>checkbox</dfn> | <dfn>radio</dfn> | <dfn>square-button</dfn> | <dfn>menulist</dfn> | <dfn>listbox</dfn> | <dfn>meter</dfn> | <dfn>progress-bar</dfn> | <dfn>button</dfn> </pre>

As far as I can tell, all other specs do not. An example of the standard declaration:
https://github.com/w3c/csswg-drafts/blob/master/css-fonts-4/Overview.bs#L866-L874

In order to better support automated parsing of these specs, I'd recommend that <compat-auto> = be removed from the value definition.