acpi: Support IBM SMBus CMI devices

On some old IBM workstations and desktop computers, the BIOS presents in the
DSDT an SMBus object that is missing the HID identifier that the i2c-scmi
driver looks for.  Modify the ACPI device scan code to insert the missing HID
if it finds an IBM system with such an object.

Affected machines: IntelliStation Z20/Z30.  Note that the i2c-i801 driver no
longer works on these machines because of ACPI resource conflicts.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>