firmware: smccc: Support optional Arm SMCCC SOC_ID name

firmware: smccc: Support optional Arm SMCCC SOC_ID name

Issue Number 1.6 of the Arm SMC Calling Convention introduces an optional
SOC_ID name string.  If implemented, point the 'machine' field of the SoC
Device Attributes at this string so that it will appear under
/sys/bus/soc/devices/soc0/machine.

On Arm SMC compliant SoCs, this will allow things like 'lscpu' to
eventually get a SoC provider model name from there rather than each
tool/utility needing to get a possibly inconsistent, obsolete, or incorrect
model/machine name from its own hardcoded model/machine name table.

Signed-off-by: Paul Benoit <paul@os.amperecomputing.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Mark Rutland <mark.rutland@arm.com>
Message-Id: <20250219005932.3466-1-paul@os.amperecomputing.com>
(sudeep.holla: Dropped regsize variable and used 8 instead as Mark suggested)
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>