MIPS: Add missing include files

After the split of linux/sched.h, several platforms in arch/mips stopped building.

Add the respective additional #include statements to fix the problem I first
tried adding these into asm/processor.h, but ran into circular header
dependencies with that which I could not figure out.

The commit I listed as causing the problem is the branch merge, as there is
likely a combination of multiple patches in that branch.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
Fixes: 1827adb11a ("Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
Link: http://lkml.kernel.org/r/20170308072931.3836696-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/mips/netlogic/xlp/cop2-ex.c

@@ -9,11 +9,14 @@
  * Copyright (C) 2009 Wind River Systems,
  *   written by Ralf Baechle <ralf@linux-mips.org>
  */
+#include <linux/capability.h>
 #include <linux/init.h>
 #include <linux/irqflags.h>
 #include <linux/notifier.h>
 #include <linux/prefetch.h>
+#include <linux/ptrace.h>
 #include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/cop2.h>
 #include <asm/current.h>