x86/cpu: Create Hygon Dhyana architecture support file

Add x86 architecture support for a new processor: Hygon Dhyana Family
18h. Carve out initialization code needed by Dhyana into a separate
compilation unit.

To identify Hygon Dhyana CPU, add a new vendor type X86_VENDOR_HYGON.

Since Dhyana uses AMD functionality to a large degree, select
CPU_SUP_AMD which provides that functionality.

 [ bp: drop explicit license statement as it has an SPDX tag already. ]

Signed-off-by: Pu Wen <puwen@hygon.cn>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: tglx@linutronix.de
Cc: mingo@redhat.com
Cc: hpa@zytor.com
Cc: x86@kernel.org
Cc: thomas.lendacky@amd.com
Link: https://lkml.kernel.org/r/1a882065223bacbde5726f3beaa70cebd8dcd814.1537533369.git.puwen@hygon.cn
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 638411f..6adce15 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -426,6 +426,20 @@
 
 	  If unsure, say N.
 
+config CPU_SUP_HYGON
+	default y
+	bool "Support Hygon processors" if PROCESSOR_SELECT
+	select CPU_SUP_AMD
+	help
+	  This enables detection, tunings and quirks for Hygon processors
+
+	  You need this enabled if you want your kernel to run on an
+	  Hygon CPU. Disabling this option on other types of CPUs
+	  makes the kernel a tiny bit smaller. Disabling it on an Hygon
+	  CPU might render the kernel unbootable.
+
+	  If unsure, say N.
+
 config CPU_SUP_CENTAUR
 	default y
 	bool "Support Centaur processors" if PROCESSOR_SELECT