Convert the devicetree bindings for the Google Security Chip H1 running
Cr50 firmware to DT schema.

The chip can be attached to SPI or I²C.  Existing devicetrees use the
same "google,cr50" compatible string for both cases without additionally
specifying a generic "tcg,tpm_tis-spi" or "tcg,tpm-tis-i2c" compatible.

The chip therefore cannot be documented in the tcg,tpm_tis-spi.yaml and
tcg,tpm-tis-i2c.yaml schemas:  The validator would select both of them
and complain about SPI properties when the chip is an I²C peripheral.

So document the chip in a schema of its own which includes both, SPI and
I²C properties by reference.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/52635205818ab201cacb0c0f37c7fa48149c7f8e.1702806810.git.lukas@wunner.deSigned-off-by: Rob Herring <robh@kernel.org>