xfs: convert remaining kmem_free() to kfree()

The remaining callers of kmem_free() are freeing heap memory, so
we can convert them directly to kfree() and get rid of kmem_free()
altogether.

This conversion was done with:

$ for f in `git grep -l kmem_free fs/xfs`; do
> sed -i s/kmem_free/kfree/ $f
> done
$

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>