soc/intel/xeon_sp: Refactor code to allow for additional CPUs types

Refactor the code and split it into Xeon common and CPU-specific code.
Move most Skylake-SP code into skx/ and keep common code in the current
folder.

This is a preparation for future work that will enable next
generation server CPU.

TEST=Tested on OCP Tioga Pass. There does not seem to be degradation
of stability as far as I could tell.

Signed-off-by: Andrey Petrov <anpetrov@fb.com>
Change-Id: I448e6cfd6a85efb83d132ad26565557fe55a265a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39601
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/intel/xeon_sp/uncore.c b/src/soc/intel/xeon_sp/uncore.c
index 34f00d8..c72c6c3 100644
--- a/src/soc/intel/xeon_sp/uncore.c
+++ b/src/soc/intel/xeon_sp/uncore.c
@@ -21,7 +21,8 @@
 #include <soc/iomap.h>
 #include <soc/pci_devs.h>
 #include <soc/ramstage.h>
-#include <soc/soc_util.h>
+#include <soc/util.h>
+#include <fsp/util.h>
 
 struct map_entry {
 	uint32_t    reg;