mpc8xx: remove spc1920 board support

This board is old enough and has no maintainer.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/doc/README.scrapyard b/doc/README.scrapyard
index d8678af..6a1d2a5 100644
--- a/doc/README.scrapyard
+++ b/doc/README.scrapyard
@@ -11,6 +11,7 @@
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+spc1920          powerpc     mpc8xx         -           -
 v37              powerpc     mpc8xx         -           -
 fads             powerpc     mpc8xx         -           -
 netphone         powerpc     mpc8xx         -           -