Convert Renesas HSPI bindings documentation to json-schema.
Also name bindings documentation file according to the compat string
being documented.

As a side effect of this change all currently supported/used compat
strings are listed while no while card compat string is documented.
This, in my opinion, is desirable as only supported hardware should
be documented.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20190916075352.32108-1-horms+renesas@verge.net.auSigned-off-by: Mark Brown <broonie@kernel.org>