Revert "bsg-lib: don't free job in bsg_prepare_job"

This reverts commit eb4375e1 which was
commit f507b54dccfd8000c517d740bc45f20c74532d18 upstream.

Ben reports:
	That function doesn't exist here (it was introduced in 4.13).
	Instead, this backport has modified bsg_create_job(), creating a
	leak.  Please revert this on the 3.18, 4.4 and 4.9 stable
	branches.

So I'm dropping it from here.

Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>