ARM: ns9750dev: remove remainders of dead board

Commit 8b710b1 started removing code for the unmaintained "ns9750dev"
board; the board support is still broken, and not included anywhere in
the Makefile or boards.cfg.  Remove the remaining dead code.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/doc/README.scrapyard b/doc/README.scrapyard
index 185bd0e..e9ca96c 100644
--- a/doc/README.scrapyard
+++ b/doc/README.scrapyard
@@ -11,6 +11,7 @@
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+ns9750dev        arm         arm926ejs      -           -           Markus Pietrek <mpietrek@fsforth.de>
 AMX860           powerpc     mpc860         1b0757e     2012-10-28  Wolfgang Denk <wd@denx.de>
 c2mon            powerpc     mpc855         1b0757e     2012-10-28  Wolfgang Denk <wd@denx.de>
 ETX094           powerpc     mpc850         1b0757e     2012-10-28  Wolfgang Denk <wd@denx.de>