common: Drop part.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/reiserfs.h b/include/reiserfs.h
index a655d5e..b61bb60 100644
--- a/include/reiserfs.h
+++ b/include/reiserfs.h
@@ -18,6 +18,9 @@
 #define SECTOR_SIZE		0x200
 #define SECTOR_BITS		9
 
+struct blk_desc;
+struct disk_partition;
+
 /* Error codes */
 typedef enum
 {