dax: quiet bdev_dax_supported()

Before we add another failure reason, quiet the existing log messages.
Leave it to the caller to decide if bdev_dax_supported() failures are
errors worth emitting to the log.
Reported-by: NJeff Moyer <jmoyer@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/dax/super.c

@@ -92,21 +92,21 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
 	long len;
 
 	if (blocksize != PAGE_SIZE) {
-		pr_err("VFS (%s): error: unsupported blocksize for dax\n",
+		pr_debug("VFS (%s): error: unsupported blocksize for dax\n",
 				sb->s_id);
 		return -EINVAL;
 	}
 
 	err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
 	if (err) {
-		pr_err("VFS (%s): error: unaligned partition for dax\n",
+		pr_debug("VFS (%s): error: unaligned partition for dax\n",
 				sb->s_id);
 		return err;
 	}
 
 	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
 	if (!dax_dev) {
-		pr_err("VFS (%s): error: device does not support dax\n",
+		pr_debug("VFS (%s): error: device does not support dax\n",
 				sb->s_id);
 		return -EOPNOTSUPP;
 	}
@@ -118,7 +118,7 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
 	put_dax(dax_dev);
 
 	if (len < 1) {
-		pr_err("VFS (%s): error: dax access failed (%ld)",
+		pr_debug("VFS (%s): error: dax access failed (%ld)\n",
 				sb->s_id, len);
 		return len < 0 ? len : -EIO;
 	}