i2c: mlxbf: add multi slave functionality

Support the multi slave functionality which enables the BlueField
to be registered at up to 16 i2c slave addresses.
Reviewed-by: Khalil Blaiech <kblaiech@nvidia.com>
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>