xfs: move some code out of xfs_iget_recycle

xfs: move some code out of xfs_iget_recycle

Having a function drop locks, reacquire them and release them again
seems to confuse the clang lock analysis even more than it confuses
humans.  Keep the humans and machines sanity by moving a chunk of
code into the caller to simplify the lock tracking.

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