ipmi: ssif_bmc: Add SSIF BMC driver

The SMBus system interface (SSIF) IPMI BMC driver can be used to perform
in-band IPMI communication with their host in management (BMC) side.

Thanks Dan for the copy_from_user() fix in the link below.

Link: https://lore.kernel.org/linux-arm-kernel/20220310114119.13736-4-quan@os.amperecomputing.com/
Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
Message-Id: <20221004093106.1653317-2-quan@os.amperecomputing.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>