powerpc: hiddendragon: remove orphan board

This board has been orphan for a while.
(Emails to its maintainer have been bouncing.)

Because MPC82xx family is old enough, nobody would pick up
the maintainership on it.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denx <wd@denx.de>
diff --git a/doc/README.scrapyard b/doc/README.scrapyard
index cbc373b..e2157e0 100644
--- a/doc/README.scrapyard
+++ b/doc/README.scrapyard
@@ -11,6 +11,7 @@
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+hidden_dragon    powerpc     mpc824x        -           -           Yusdi Santoso <yusdi_santoso@adaptec.com>
 debris           powerpc     mpc824x        -           -           Sangmoon Kim <dogoil@etinsys.com>
 kvme080          powerpc     mpc824x        -           -           Sangmoon Kim <dogoil@etinsys.com>
 ep8248           powerpc     mpc8260        -           -           Yuli Barcohen <yuli@arabellasw.com>