[PATCH] lockdep: annotate the BLKPG_DEL_PARTITION ioctl

The delete partition IOCTL takes the bd_mutex for both the disk and the
partition; these have an obvious hierarchical relationship and this patch
annotates this relationship for lockdep.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>