SMBUS_BLOCK_DATA transactions might fail due to a race condition with
the IMC (Integrated Micro Controller), even when the IMC semaphore
is used.

This bug has been reported and confirmed by AMD, who suggested as a
solution an IMC firmware upgrade (obtained via BIOS update) and
disabling the IMC during SMBUS_BLOCK_DATA transactions.

Even without the IMC upgrade, the SMBUS is much more stable with this
patch.

Tested on a Bettong-alike board.
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-by: NJean Delvare <jdelvare@suse.de>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>