sb/intel/i82801dx: Correct SMBUS_IO_BASE value

The current value of 0x1000 would overlap the first PCI bridge IO
window. As we commonly reserve IO range 0x0 .. 0x1000 for LPC and
integrated device use, change SMBUS_IO_BASE to 0x400. This is the
prevalent value among Intel southbridges, too.

Change-Id: I5c299f001f9012d6766b155a2f5def5cff6e88d1
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43023
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/southbridge/intel/i82801dx/i82801dx.h

@@ -94,7 +94,7 @@ void aseg_smm_lock(void);
 #define RTC_FAILED      (1 <<2)
 
 
-#define SMBUS_IO_BASE 0x1000
+#define SMBUS_IO_BASE	0x400
 
 #define PM1_STS		0x00
 #define   WAK_STS	(1 << 15)