powerpc/mm: Move book3s64 specifics in subdirectory mm/book3s64

Many files in arch/powerpc/mm are only for book3S64. This patch
creates a subdirectory for them.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Update the selftest sym links, shorten new filenames, cleanup some
      whitespace and formatting in the new files.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/book3s64/vphn.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ARCH_POWERPC_MM_VPHN_H_
+#define _ARCH_POWERPC_MM_VPHN_H_
+
+/* The H_HOME_NODE_ASSOCIATIVITY h_call returns 6 64-bit registers. */
+#define VPHN_REGISTER_COUNT 6
+
+/*
+ * 6 64-bit registers unpacked into up to 24 be32 associativity values. To
+ * form the complete property we have to add the length in the first cell.
+ */
+#define VPHN_ASSOC_BUFSIZE (VPHN_REGISTER_COUNT*sizeof(u64)/sizeof(u16) + 1)
+
+extern int vphn_unpack_associativity(const long *packed, __be32 *unpacked);
+
+#endif