libnvme: git submodule update

Update libnvme to pull in map file updates.

diff --git a/libnvme b/libnvme
index b310ad7439218d22758ee06b4a91402cf98202e9..fef2156256d7ceabd555b9ba079846abbf864891 160000 (submodule)
--- a/libnvme
+++ b/libnvme
@@ -1 +1 @@
-Subproject commit b310ad7439218d22758ee06b4a91402cf98202e9
+Subproject commit fef2156256d7ceabd555b9ba079846abbf864891