Delay bsg unregistration, because we want to wait until all the request/cmds
have released their reference.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>