MIPS: Prune some target specific code out of prom.c

This code is not common enough to be in a shared file.  It is also not
used by any existing boards, so just remove it.

[ralf@linux-mips.org: Dropped removal of irq_create_of_mapping which was
already removed by abd2363f6a
[irq_domain/mips: Allow irq_domain on MIPS].  Moved device_tree_init() and
dependencies to its sole user, the XLP code.]

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree-discuss@lists.ozlabs.org
Cc: grant.likely@secretlab.ca
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2946/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/netlogic/xlp/Makefile

@@ -1,2 +1,3 @@
 obj-y				+= setup.o platform.o nlm_hal.o
+obj-$(CONFIG_OF)		+= of.o
 obj-$(CONFIG_SMP)		+= wakeup.o

arch/mips/netlogic/xlp/of.c

@@ -0,0 +1,34 @@
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of_fdt.h>
+#include <asm/byteorder.h>
+
+static int __init reserve_mem_mach(unsigned long addr, unsigned long size)
+{
+	return reserve_bootmem(addr, size, BOOTMEM_DEFAULT);
+}
+
+void __init free_mem_mach(unsigned long addr, unsigned long size)
+{
+	return free_bootmem(addr, size);
+}
+
+void __init device_tree_init(void)
+{
+	unsigned long base, size;
+
+	if (!initial_boot_params)
+		return;
+
+	base = virt_to_phys((void *)initial_boot_params);
+	size = be32_to_cpu(initial_boot_params->totalsize);
+
+	/* Before we do anything, lets reserve the dt blob */
+	reserve_mem_mach(base, size);
+
+	unflatten_device_tree();
+
+	/* free the space reserved for the dt blob */
+	free_mem_mach(base, size);
+}