sparc: explicitly include sched.h to get task_thread_info declaration

This was caused by commit 16559ae48c76 ("kgdb: remove #include
<linux/serial_8250.h> from kgdb.h") from the tty tree.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/sparc/kernel/kgdb_32.c

@@ -5,6 +5,7 @@
 
 #include <linux/kgdb.h>
 #include <linux/kdebug.h>
+#include <linux/sched.h>
 
 #include <asm/kdebug.h>
 #include <asm/ptrace.h>