Add BlueField I2C driver to offer master and slave support for
Mellanox BlueField SoCs. The driver implements an SMBus adapter
and interfaces to multiple busses that can be probed using both
ACPI and Device Tree infrastructures.

The driver supports several SMBus operations to transfer data
back and forth from/to various I2C devices. It is mainly intended
to be consumed by userspace tools and utilities, such as i2c-tools
and decode-dimms to collect memory module information.

On the other hand, the driver has a slave function to support,
among others, an IPMB interface that requires both master and
slave functions to handle transfers between the BlueField SoC
and a board management controllers (e.g., BMC).

Signed-off-by: Khalil Blaiech <kblaiech@mellanox.com>
Reviewed-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>