ide: Accept the IDLE (0xe3) ATA command.

This command is supposed to set up a timer which will put the drive into a
standby mode if it isn't sent a command within a given time out. Since most of
the timeouts are generally significantly longer than a simulation would run
anyway, and we don't have an implementation for standby mode to begin with,
we can accept the command, do nothing, and report success.

src/dev/ide_disk.cc

@@ -645,6 +645,7 @@ IdeDisk::startCommand()
       case WDSF_SEEK:
       case SET_FEATURES:
       case WDCC_SETMULTI:
+      case WDCC_IDLE:
         devState = Command_Execution;
         action = ACT_CMD_COMPLETE;
         break;