Fix pmem build error
Fix pmem build error

* Fix 'pmem declared and not used' build error introduced with https://github.com/microsoft/opengcs/pull/375.
When testing things to solve the 5.4 kernel build failure I had been doing all of
the work on a '54-kernel-failure' branch, so when we discovered the dax issue I
added the fix to this branch and built off of it to verify. When seeing that this
resolved the issue I created a new branch and just added the removing of dax changes
and forgot to add what is in this commit before pushing.

Signed-off-by: Daniel Canter <8d0fd95ae71f7e4870b010b10f83a6201b034a65@microsoft.com>

Microsoft/hcsshim,rn/opengcs,rn/opengcs