libnvdimm: IS_ERR() usage cleanup

Prompted by commit 287980e49ffc "remove lots of IS_ERR_VALUE abuses", I
ran make coccicheck against drivers/nvdimm/ and found that:

	if (IS_ERR(x))
		return PTR_ERR(x);
	return 0;

...can be replaced with PTR_ERR_OR_ZERO().

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
index 8b2e3c4..9997ff9 100644
--- a/drivers/nvdimm/claim.c
+++ b/drivers/nvdimm/claim.c
@@ -266,9 +266,8 @@
 
 	nsio->addr = devm_memremap(dev, res->start, resource_size(res),
 			ARCH_MEMREMAP_PMEM);
-	if (IS_ERR(nsio->addr))
-		return PTR_ERR(nsio->addr);
-	return 0;
+
+	return PTR_ERR_OR_ZERO(nsio->addr);
 }
 EXPORT_SYMBOL_GPL(devm_nsio_enable);