libnvdimm fix for v5.9-rc5

Fix decetion of dax support for block devices. Previous fixes in this
 area, which only affected printing of debug messages, had an incorrect
 condition for detection of dax. This fix should finally do the right thing.
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Merge tag 'libnvdimm-fix-v5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm fix from Vishal Verma:
 "Fix detection of dax support for block devices.

  Previous fixes in this area, which only affected printing of debug
  messages, had an incorrect condition for detection of dax. This fix
  should finally do the right thing"

* tag 'libnvdimm-fix-v5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: fix detection of dax support for non-persistent memory block devices

drivers/dax/super.c

@@ -100,7 +100,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
 		return false;
 	}
 
-	if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
+	if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
 		pr_debug("%s: error: dax unsupported by block device\n",
 				bdevname(bdev, buf));
 		return false;