swiotlb: clean up swiotlb_tbl_unmap_single

swiotlb: clean up swiotlb_tbl_unmap_single

commit: ca10d0f8e530600ec63c603dbace2c30927d70b7

swiotlb: clean up swiotlb_tbl_unmap_single

Remove a layer of pointless indentation, replace a hard to follow
ternary expression with a plain if/else.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>