powerpc/svm: stop using io_tlb_start

Use the local variable that is passed to swiotlb_init_with_tbl for
freeing the memory in the failure case to isolate the code a little
better from swiotlb internals.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/powerpc/platforms/pseries/svm.c

@@ -55,9 +55,9 @@ void __init svm_swiotlb_init(void)
 	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, false))
 		return;
 
-	if (io_tlb_start)
-		memblock_free_early(io_tlb_start,
-				    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+
+	memblock_free_early(__pa(vstart),
+			    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 	panic("SVM: Cannot allocate SWIOTLB buffer");
 }