Revert "Bluetooth: fix shutdown on SCO sockets"

This reverts commit f21ca5fff6e548833fa5ee8867239a8378623150.

Quoth Gustavo F. Padovan:
  "Commit f21ca5fff6e548833fa5ee8867239a8378623150 can cause a NULL
   dereference if we call shutdown in a bluetooth SCO socket and doesn't
   wait the shutdown completion to call close().  Please revert it.  I
   may have a fix for it soon, but we don't have time anymore, so revert
   is the way to go.  ;)"

Requested-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>