omap: remove omap5912osk board support

Emails to the board maintainer
"Rishi Bhattacharya <rishi@ti.com>"
have been bouncing.

Tom suggested to remove this board.

Remove also omap1510_udc.c because this is the last board
to enable it.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Suggested-by: Tom Rini <trini@ti.com>
diff --git a/doc/README.scrapyard b/doc/README.scrapyard
index b950a41..6f28ab0 100644
--- a/doc/README.scrapyard
+++ b/doc/README.scrapyard
@@ -12,6 +12,7 @@
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+omap5912osk      arm         arm926ejs      -           -           Rishi Bhattacharya <rishi@ti.com>
 p1023rds         powerpc     mpc85xx        d0bc5140    2014-07-22  Roy Zang <tie-fei.zang@freescale.com>
 spc1920          powerpc     mpc8xx         98ad54be    2014-07-07
 v37              powerpc     mpc8xx         b8c1438a    2014-07-07