ref: 9e10006451cd753ab55cc2fd062b1387d3e281bf drmdb/drmtree d---------
drmtree: handle USB devices

References: https://github.com/ascent12/drm_info/pull/49
drmtree: fix empty IN_FORMATS handling

Some drivers expose an empty IN_FORMATS prop (e.g. exynos).
Pretty-print enums spec
Add a property page
Use String helpers for modifiers and formats
Add formats page
Fix driver comparison
drmtree: slightly improve modifier pretty-printing
drmtree: pretty-print prop spec
drmtree: pretty-print type-specific property data
drmtree: print whether a prop is immutable/atomic
drmtree: sort maps in FormatTree
Add device page
drmtree: add kernel field
Add basic support for platform devices
Add a /drivers page
Add a /properties page
Fix and improve JSON property unmarshalling