swiotlb: Minor fix-ups for DMA_ATTR_SKIP_CPU_SYNC support

I am updating the paths so that instead of trying to pass
"attr | DMA_ATTR_SKIP_CPU_SYNC" we instead just OR the value into attr and
then pass it since attr will not be used after we make the unmap call.

I realized there was one spot I had missed when I was applying the DMA
attribute to the DMA mapping exception handling.  This change corrects that.

Finally it looks like there is a stray blank line at the end of the
swiotlb_unmap_sg_attrs function that can be dropped.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>