plugins/sed: Fix uninitialized variable

plugins/sed: Fix uninitialized variable

../plugins/sed/sedopal_cmd.c: In function ‘sedopal_cmd_discover’:
../plugins/sed/sedopal_cmd.c:506:17: warning: ‘locking_flags’ may be used uninitialized [-Wmaybe-uninitialized]
  506 |                 sedopal_print_locking_features(locking_flags);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../plugins/sed/sedopal_cmd.c:459:17: note: ‘locking_flags’ was declared here
  459 |         uint8_t locking_flags;
      |                 ^~~~~~~~~~~~~

Signed-off-by: Tomas Bzatek <tbzatek@redhat.com>