[PATCH] USB: rmmod pl2303 after -28

Wait for the scheduled work to finish before freeing memory, prevent oops.
http://bugzilla.kernel.org/show_bug.cgi?id=6596



Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>