powerpc: Move page table dump files in a dedicated subdirectory

This patch moves the files related to page table dump in a
dedicated subdirectory.

The purpose is to clean a bit arch/powerpc/mm by regrouping
multiple files handling a dedicated function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Shorten the file names while we're at it]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/ptdump/shared.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * From split of dump_linuxpagetables.c
+ * Copyright 2016, Rashmica Gupta, IBM Corp.
+ *
+ */
+#include <linux/kernel.h>
+#include <asm/pgtable.h>
+
+#include "ptdump.h"
+
+static const struct flag_info flag_array[] = {
+	{
+		.mask	= _PAGE_USER,
+		.val	= _PAGE_USER,
+		.set	= "user",
+		.clear	= "    ",
+	}, {
+		.mask	= _PAGE_RW,
+		.val	= _PAGE_RW,
+		.set	= "rw",
+		.clear	= "r ",
+	}, {
+		.mask	= _PAGE_EXEC,
+		.val	= _PAGE_EXEC,
+		.set	= " X ",
+		.clear	= "   ",
+	}, {
+		.mask	= _PAGE_PRESENT,
+		.val	= _PAGE_PRESENT,
+		.set	= "present",
+		.clear	= "       ",
+	}, {
+		.mask	= _PAGE_GUARDED,
+		.val	= _PAGE_GUARDED,
+		.set	= "guarded",
+		.clear	= "       ",
+	}, {
+		.mask	= _PAGE_DIRTY,
+		.val	= _PAGE_DIRTY,
+		.set	= "dirty",
+		.clear	= "     ",
+	}, {
+		.mask	= _PAGE_ACCESSED,
+		.val	= _PAGE_ACCESSED,
+		.set	= "accessed",
+		.clear	= "        ",
+	}, {
+		.mask	= _PAGE_WRITETHRU,
+		.val	= _PAGE_WRITETHRU,
+		.set	= "write through",
+		.clear	= "             ",
+	}, {
+		.mask	= _PAGE_NO_CACHE,
+		.val	= _PAGE_NO_CACHE,
+		.set	= "no cache",
+		.clear	= "        ",
+	}, {
+		.mask	= _PAGE_SPECIAL,
+		.val	= _PAGE_SPECIAL,
+		.set	= "special",
+	}
+};
+
+struct pgtable_level pg_level[5] = {
+	{
+	}, { /* pgd */
+		.flag	= flag_array,
+		.num	= ARRAY_SIZE(flag_array),
+	}, { /* pud */
+		.flag	= flag_array,
+		.num	= ARRAY_SIZE(flag_array),
+	}, { /* pmd */
+		.flag	= flag_array,
+		.num	= ARRAY_SIZE(flag_array),
+	}, { /* pte */
+		.flag	= flag_array,
+		.num	= ARRAY_SIZE(flag_array),
+	},
+};