xfs: return the allocated transaction from xfs_trans_alloc_empty

Source kernel commit: d8e1ea43e5a314bc01ec059ce93396639dcf9112

xfs_trans_alloc_empty can't return errors, so return the allocated
transaction directly instead of an output double pointer argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
16 files changed