kernel: move old "rootfs" splitter into separated file

This will simplify removing it in the future.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

SVN-Revision: 42828

target/linux/generic/patches-3.14/405-mtd-add-more-helper-functions.patch

@@ -18,7 +18,7 @@
  	}
  	if (slave->offset == MTDPART_OFS_RETAIN) {
  		slave->offset = cur_offset;
-@@ -989,6 +987,24 @@ int mtd_is_partition(const struct mtd_in
+@@ -944,6 +942,24 @@ int mtd_is_partition(const struct mtd_in
  }
  EXPORT_SYMBOL_GPL(mtd_is_partition);