[PATCH] coverity: udf/balloc.c null deref fix

It's doing

	if (obh)
		<stuff>
	else
		dereference obh

So presumably `obh' is never null in there.

This defect was found automatically by Coverity Prevent, a static analysis
tool.

Signed-off-by: Zaur Kambarov <zkambarov@coverity.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>