sparc: Eliminate prom_stdin.

Completely unused.

Based upon a patch by Julian Calaby.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/oplib_64.h b/arch/sparc/include/asm/oplib_64.h
index 8cd0df3..97a9047 100644
--- a/arch/sparc/include/asm/oplib_64.h
+++ b/arch/sparc/include/asm/oplib_64.h
@@ -18,8 +18,8 @@
  */
 extern phandle prom_root_node;
 
-/* PROM stdin and stdout */
-extern int prom_stdin, prom_stdout;
+/* PROM stdout */
+extern int prom_stdout;
 
 /* /chosen node of the prom device tree, this stays constant after
  * initialization is complete.