vfio/type1: Fix vfio_find_dma_valid return

vfio_find_dma_valid is defined to return WAITED on success if it was
necessary to wait.  However, the loop forgets the WAITED value returned
by vfio_wait() and returns 0 in a later iteration.  Fix it.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/r/1629736550-2388-1-git-send-email-anthony.yznaga@oracle.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Author: Anthony Yznaga

drivers/vfio/vfio_iommu_type1.c

@@ -612,17 +612,17 @@ static int vfio_wait(struct vfio_iommu *iommu)
 static int vfio_find_dma_valid(struct vfio_iommu *iommu, dma_addr_t start,
 			       size_t size, struct vfio_dma **dma_p)
 {
-	int ret;
+	int ret = 0;
 
 	do {
 		*dma_p = vfio_find_dma(iommu, start, size);
 		if (!*dma_p)
-			ret = -EINVAL;
+			return -EINVAL;
 		else if (!(*dma_p)->vaddr_invalid)
-			ret = 0;
+			return ret;
 		else
 			ret = vfio_wait(iommu);
-	} while (ret > 0);
+	} while (ret == WAITED);
 
 	return ret;
 }