x86: nmi - consolidate nmi_watchdog_default for 32bit mode

64bit mode bootstrap code does set nmi_watchdog to NMI_NONE
by default and doing the same on 32bit mode is safe too.
Such an action saves us from several #ifdef.

Btw, my previous commit

commit 19ec673ced067316b9732bc6d1c4ff4052e5f795
Author: Cyrill Gorcunov <gorcunov@gmail.com>
Date:   Wed May 28 23:00:47 2008 +0400

    x86: nmi - fix incorrect NMI watchdog used by default

did not fix the problem completely, moreover it
introduced additional bug - nmi_watchdog would be
set to either NMI_LOCAL_APIC or NMI_IO_APIC
_regardless_ to boot option if being enabled thru
/proc/sys/kernel/nmi_watchdog. Sorry for that.
Fix it too.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: mingo@redhat.com
Cc: hpa@zytor.com
Cc: macro@linux-mips.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/nmi.c

@@ -487,14 +487,16 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
 		return -EIO;
 	}
 
-#ifdef CONFIG_X86_64
 	/* if nmi_watchdog is not set yet, then set it */
 	nmi_watchdog_default();
-#else
-	if (lapic_watchdog_ok())
-		nmi_watchdog = NMI_LOCAL_APIC;
-	else
-		nmi_watchdog = NMI_IO_APIC;
+
+#ifdef CONFIG_X86_32
+	if (nmi_watchdog == NMI_NONE) {
+		if (lapic_watchdog_ok())
+			nmi_watchdog = NMI_LOCAL_APIC;
+		else
+			nmi_watchdog = NMI_IO_APIC;
+	}
 #endif
 
 	if (nmi_watchdog == NMI_LOCAL_APIC) {

include/asm-x86/nmi.h

@@ -38,12 +38,10 @@ static inline void unset_nmi_pm_callback(struct pm_dev *dev)
 
 #ifdef CONFIG_X86_64
 extern void default_do_nmi(struct pt_regs *);
-extern void nmi_watchdog_default(void);
-#else
-#define nmi_watchdog_default() do { } while (0)
 #endif
 
 extern void die_nmi(char *str, struct pt_regs *regs, int do_panic);
+extern void nmi_watchdog_default(void);
 extern int check_nmi_watchdog(void);
 extern int nmi_watchdog_enabled;
 extern int avail_to_resrv_perfctr_nmi_bit(unsigned int);