AMD K8 fam10: Refactor Kconfig SB_HT_CHAIN_ON_BUS0

If SB_HT_CHAIN_ON_BUS0 is selected, HyperTransport chain for System Bus
is the first to scan and it will be assigned with bus number 0.

If HT_CHAIN_DISTRIBUTE is selected, each link will reserve a fixed range
of bus numbers instead of assigning consecutive numbers across all the links.

All fam10 have SB_HT_CHAIN_ON_BUS0 selected under northbridge.
Follow-up can easily drop this if we find this is dictated by architecture.

Change-Id: I8deddcb4c3fd679b6b27e2879d9dba3895c4dd6f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/8366
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>

src/mainboard/sunw/ultra40/Kconfig

@@ -5,6 +5,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select CPU_AMD_SOCKET_940
 	select NORTHBRIDGE_AMD_AMDK8
 	select SOUTHBRIDGE_NVIDIA_CK804
+	select HT_CHAIN_DISTRIBUTE
 	select SUPERIO_SMSC_LPC47B397
 	select SUPERIO_SMSC_LPC47M10X
 	select HAVE_OPTION_TABLE
@@ -56,10 +57,6 @@ config HT_CHAIN_UNITID_BASE
 	hex
 	default 0x0
 
-config SB_HT_CHAIN_ON_BUS0
-	int
-	default 2
-
 config IRQ_SLOT_COUNT
 	int
 	default 11