hwdb: allow list of lookup keys per given record

This allows to specify:
  dmi:bvn*:bvr*:bd*:svnVENDOR:pn:Model 231*:pvr*
  dmi:bvn*:bvr*:bd*:svnVENDOR:pn:Series 12*:pvr*
   KEY_A=value
   KEY_B=value

Instead of:
  dmi:bvn*:bvr*:bd*:svnVENDOR:pn:Model 231*:pvr*
   KEY_A=value
   KEY_B=value

  dmi:bvn*:bvr*:bd*:svnVENDOR:pn:Series 12*:pvr*
   KEY_A=value
   KEY_B=value