nvdimm/pmem: Set dax flag for all 'PFN_MAP' cases

The dax is only supported on pfn type pmem devices since commit
f467fee ("block: move the dax flag to queue_limits"). Trying
to mount DAX filesystem fails with this error:
 mount: : wrong fs type, bad option, bad superblock on /dev/pmem7,
          missing codepage or helper program, or other error.
 dmesg(1) may have more information after failed mount system call.
 dmesg: EXT4-fs (pmem7): DAX unsupported by block device.

Fix the problem by adding dax flag setting for the missed case.

Fixes: f467fee ("block: move the dax flag to queue_limits")
Signed-off-by: Zhihao Cheng <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Tested-by: Ira Weiny <[email protected]>
Tested-by: Alison Schofield <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Ira Weiny <[email protected]>

Author: Zhihao Cheng

drivers/nvdimm/pmem.c

@@ -498,7 +498,7 @@ static int pmem_attach_disk(struct device *dev,
 	}
 	if (fua)
 		lim.features |= BLK_FEAT_FUA;
-	if (is_nd_pfn(dev))
+	if (is_nd_pfn(dev) || pmem_should_map_pages(dev))
 		lim.features |= BLK_FEAT_DAX;
 
 	if (!devm_request_mem_region(dev, res->start, resource_size(res),