dt-bindings: Add SynQucer TPM MMIO as a trivial device

Add a compatible string for the SynQuacer TPM to the binding for a
TPM exposed via a memory mapped TIS frame. The MMIO window behaves
slightly differently on this hardware, so it requires its own
identifier.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>