x86/watchdog: Fix Kconfig help text file path reference to lockup watchdog documentation

Signed-off-by: Benjamin Peterson <bp@benjamin.pe>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 9919cba7 ("watchdog: Update documentation")
Link: http://lkml.kernel.org/r/20170521002016.13258-1-bp@benjamin.peSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig

@@ -360,7 +360,7 @@ config SMP
 	  Management" code will be disabled if you say Y here.
 
 	  See also <file:Documentation/x86/i386/IO-APIC.txt>,
-	  <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
+	  <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
 	  <http://www.tldp.org/docs.html#howto>.
 
 	  If you don't know what to do here, say N.