xfs: fix double free in xlog_recover_commit_trans

When an error occurs during buffer submission in
xlog_recover_commit_trans(), we free the trans structure twice. Fix
it by only freeing the structure in the caller regardless of the
success or failure of the function.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>