mm: cleanup to make remove_memory() arch-neutral

There is nothing architecture specific about remove_memory().
remove_memory() function is common for all architectures which support
hotplug memory remove.  Instead of duplicating it in every architecture,
collapse them into arch neutral function.

[akpm@linux-foundation.org: fix the export]
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/powerpc/mm/mem.c

@@ -134,23 +134,6 @@ int arch_add_memory(int nid, u64 start, u64 size)
 
 	return __add_pages(zone, start_pfn, nr_pages);
 }
-
-#ifdef CONFIG_MEMORY_HOTREMOVE
-int remove_memory(u64 start, u64 size)
-{
-	unsigned long start_pfn, end_pfn;
-	int ret;
-
-	start_pfn = start >> PAGE_SHIFT;
-	end_pfn = start_pfn + (size >> PAGE_SHIFT);
-	ret = offline_pages(start_pfn, end_pfn, 120 * HZ);
-	if (ret)
-		goto out;
-	/* Arch-specific calls go here - next patch */
-out:
-	return ret;
-}
-#endif /* CONFIG_MEMORY_HOTREMOVE */
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 /*