sh: nmi_debug: fix return value of __setup handler

__setup() handlers should return 1 to obsolete_checksetup() in
init/main.c to indicate that the boot option has been handled.
A return of 0 causes the boot option/value to be listed as an Unknown
kernel parameter and added to init's (limited) argument or environment
strings. Also, error return codes don't mean anything to
obsolete_checksetup() -- only non-zero (usually 1) or zero.
So return 1 from nmi_debug_setup().

Fixes: 1e1030dc ("sh: nmi_debug support.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <izh1979@gmail.com>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Cc: stable@vger.kernel.org
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20230306040037.20350-3-rdunlap@infradead.orgSigned-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

arch/sh/kernel/nmi_debug.c

@@ -49,7 +49,7 @@ static int __init nmi_debug_setup(char *str)
 	register_die_notifier(&nmi_debug_nb);
 
 	if (*str != '=')
-		return 0;
+		return 1;
 
 	for (p = str + 1; *p; p = sep + 1) {
 		sep = strchr(p, ',');
@@ -70,6 +70,6 @@ static int __init nmi_debug_setup(char *str)
 			break;
 	}
 
-	return 0;
+	return 1;
 }
 __setup("nmi_debug", nmi_debug_setup);