iommu/rockchip: Silence attaching and detaching of devices

Currently the driver emits a log line every time a device
attaches or detaches - which happens at every unblank/blank
of the drm for example.  The message itself also has no real
value to the average user and is merely useful when
debugging a problem, so make it a dev_dbg instead.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 31004c0..37f6a59 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -785,7 +785,7 @@
 	list_add_tail(&iommu->node, &rk_domain->iommus);
 	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
 
-	dev_info(dev, "Attached to iommu domain\n");
+	dev_dbg(dev, "Attached to iommu domain\n");
 
 	rk_iommu_disable_stall(iommu);
 
@@ -819,7 +819,7 @@
 
 	iommu->domain = NULL;
 
-	dev_info(dev, "Detached from iommu domain\n");
+	dev_dbg(dev, "Detached from iommu domain\n");
 }
 
 static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)