[coreboot] [PATCH] Add superiotool detection support for W83667HG

[David Bartley]

This chip is present on the ASUS P6T Deluxe V2. The datasheet is not
public but I've sent a request to get it.

$ sudo ./superiotool
superiotool r4931
Found Winbond W83667HG (id=0xa5, rev=0x13) at 0x2e

Signed-off-by: David Bartley