AMD K8: Move SB_HT_CHAIN_ON_BUS0 default 0

Define the default value under northbridge. The list of boards this
patchset touches will change to use SB_HT_CHAIN_ON_BUS0 with
follow-up patch.

Based on code analysis, these boards already scan system bus
as the first (active) HT chain, so it is placed as bus 0
even when this option was not explicitly selected.

Change-Id: I5a00d6372cb89151940aeee517ea613398825c78
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/8353
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>

src/mainboard/ibm/e325/Kconfig

@@ -43,10 +43,6 @@ config MAX_PHYSICAL_CPUS
 	int
 	default 1
 
-config SB_HT_CHAIN_ON_BUS0
-	int
-	default 0
-
 config HT_CHAIN_END_UNITID_BASE
 	hex
 	default 0x20

src/mainboard/ibm/e326/Kconfig

@@ -43,10 +43,6 @@ config MAX_PHYSICAL_CPUS
 	int
 	default 2
 
-config SB_HT_CHAIN_ON_BUS0
-	int
-	default 0
-
 config HT_CHAIN_END_UNITID_BASE
 	hex
 	default 0x20