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/northbridge/amd/amdfam10/Kconfig

@@ -64,6 +64,12 @@ config SB_HT_CHAIN_UNITID_OFFSET_ONLY
 	bool
 	default n
 
+config SB_HT_CHAIN_ON_BUS0
+	def_bool y
+
+config HT_CHAIN_DISTRIBUTE
+	def_bool n
+
 config DIMM_FBDIMM
 	bool
 	default n