i2c: piix4: Use different message for AMD Auxiliary SMBus Controller

Same messages for AMD main and auxiliary SMBus controllers lead to confusion,
this patch is to remove confusion and keep consistent with non-AMD products.

Signed-off-by: Shane Huang <shane.huang@amd.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>