4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathieu Malaterre <redacted>

commit 81bd415c91eb966118d773dddf254aebf3022411 upstream.

The split out of the hard lockup detector exposed two new weak functions,
but no prototypes for them, which triggers the build warning:

  kernel/watchdog.c:109:12: warning: no previous prototype for ‘watchdog_nmi_enable’ [-Wmissing-prototypes]
  kernel/watchdog.c:115:13: warning: no previous prototype for ‘watchdog_nmi_disable’ [-Wmissing-prototypes]

Add the prototypes.

Fixes: 73ce0511c436 ("kernel/watchdog.c: move hardlockup detector to separate file")
Signed-off-by: Mathieu Malaterre <redacted>
Signed-off-by: Thomas Gleixner <redacted>
Cc: Babu Moger <redacted>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180606194232.17653-1-malat@debian.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/nmi.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h

@@ -113,6 +113,8 @@ static inline int hardlockup_detector_pe
 void watchdog_nmi_stop(void);
 void watchdog_nmi_start(void);
 int watchdog_nmi_probe(void);
+int watchdog_nmi_enable(unsigned int cpu);
+void watchdog_nmi_disable(unsigned int cpu);
 
 /**
  * touch_nmi_watchdog - restart NMI watchdog timeout.