eeprom: Add IDT 89HPESx driver bindings file

IDT 89HPESx PCIe-switches exposes SMBus interface to have an access to
the device CSRs and EEPROM. So to properly utilize the interface
functionality, developer should declare a valid dts-file node, which
would refer to the corresponding 89HPESx device.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>