iommu=pt is a valid early param

This avoids a "Malformed early option 'iommu'" warning on boot when 
trying to use pass-through mode.
Signed-off-by: NAlex Williamson <alex.williamson@hp.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

arch/x86/kernel/pci-dma.c

@@ -212,10 +212,8 @@ static __init int iommu_setup(char *p)
 		if (!strncmp(p, "soft", 4))
 			swiotlb = 1;
 #endif
-		if (!strncmp(p, "pt", 2)) {
+		if (!strncmp(p, "pt", 2))
 			iommu_pass_through = 1;
-			return 1;
-		}
 
 		gart_parse_options(p);