libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid

libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid

The EOPNOTSUPP return code from the pmem driver indicates that the
namespace has a configuration that may be valid, but the current kernel
does not support it. Expand this to all of the nd_pfn_validate() error
conditions after the infoblock has been verified as self consistent.

This prevents exposing the namespace to I/O when the infoblock needs to
be corrected, or the system needs to be put into a different
configuration (like changing the page size on PowerPC).

Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>