x86/amd_nb: Restrict init function to AMD-based systems

The code implicitly operates on AMD-based systems by matching on PCI
IDs. However, the use of these IDs is going away.

Add an explicit CPU vendor check instead of relying on PCI IDs.

Signed-off-by: Yazen Ghannam <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: yghannam

arch/x86/kernel/amd_nb.c

@@ -582,6 +582,10 @@ static __init void fix_erratum_688(void)
 
 static __init int init_amd_nbs(void)
 {
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
+	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
+		return 0;
+
 	amd_cache_northbridges();
 	amd_cache_gart();