Remove panic from phonedev.  See

	http://bugzilla.kernel.org/show_bug.cgi?id=9266

for details (phonedev panics if unregistering device not registered).
Signed-off-by: NMatti Linnanvuori <mattilinnanvuori@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>