powerpc: remove RPXClassic, RPXlite boards support

Enough time has passed since these boards were moved to Orphan. Remove.

 - Remove board/RPXlite/*
 - Remove board/RPXClassic/*
 - Remove include/configs/RPXlite.h
 - Remove include/configs/RPXClassic.h
 - Clean-up defined(CONFIG_RPXCLASSIC)
 - Move the entry from boards.cfg to doc/README.scrapyard

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/doc/README.scrapyard b/doc/README.scrapyard
index b068544..9915500 100644
--- a/doc/README.scrapyard
+++ b/doc/README.scrapyard
@@ -11,6 +11,8 @@
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+RPXClassic       powerpc     mpc8xx         -           2014-04-04
+RPXlite          powerpc     mpc8xx         -           2014-04-04
 genietv          powerpc     mpc8xx         -           2014-04-04
 mbx8xx           powerpc     mpc8xx         -           2014-04-04
 nx823            powerpc     mpc8xx         -           2014-04-04