[PATCH] s390: dasd proc entries

The proc_mkdir calls in the dasd driver are not check for NULL pointers.  Add
code to check the pointers and bail out if one of the proc entries could not
be created.

Signed-off-by: Horst Hummel <horst.hummel@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>