tools/power turbostat: Provide better debug messages for failed capabilities accesses

turbostat reports some capabilities access errors and not others.  Provide
the same debug message for all errors.

[lenb: remove extra quotes]

Cc: David Arcari <darcari@redhat.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>