nb/amd/pi/00730F01/northbridge: always return 1 in get_node_nums

This APU is always a single-node system and bits 4..6 of the node ID
register D18F0x60 are also marked as reserved in BKDG #52740 Rev 3.05.
On an APU2 board with quad-core APU, this register reads back 0x00030000
which results in a value of 1 to be returned from get_node_nums, so this
patch doesn't change behavior, but stops using reserved bits.

TEST=PC Engines APU2 still boots and doesn't show any new problems

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I65ed1124c0ca8e7eba54ff53dc626d35cd5e2e58
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79603
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/northbridge/amd/pi/00730F01/northbridge.c b/src/northbridge/amd/pi/00730F01/northbridge.c
index 9d92162..27e08c8 100644
--- a/src/northbridge/amd/pi/00730F01/northbridge.c
+++ b/src/northbridge/amd/pi/00730F01/northbridge.c
@@ -40,21 +40,9 @@
 	return pcidev_on_root(DEV_CDB + nodeid, fn);
 }
 
-static struct device *get_mc_dev(void)
-{
-	return pcidev_on_root(DEV_CDB, 0);
-}
-
 static unsigned int get_node_nums(void)
 {
-	static unsigned int node_nums;
-
-	if (node_nums)
-		return node_nums;
-
-	node_nums = ((pci_read_config32(get_mc_dev(), 0x60) >> 4) & 7) + 1; //NodeCnt[2:0]
-
-	return node_nums;
+	return 1;
 }
 
 static void get_fx_devs(void)