kgdbts: fix return value of __setup handler

__setup() handlers should return 1 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)
environment strings. So return 1 from kgdbts_option_setup().

Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc7
  kgdboc=kbd kgdbts=", will be passed to user space.

 Run /sbin/init as init process
   with arguments:
     /sbin/init
   with environment:
     HOME=/
     TERM=linux
     BOOT_IMAGE=/boot/bzImage-517rc7
     kgdboc=kbd
     kgdbts=

Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Fixes: e8d31c204e ("kgdb: add kgdb internal test suite")
Cc: kgdb-bugreport@lists.sourceforge.net
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220308033255.22118-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/kgdbts.c

@@ -1070,10 +1070,10 @@ static int kgdbts_option_setup(char *opt)
 {
 	if (strlen(opt) >= MAX_CONFIG_LEN) {
 		printk(KERN_ERR "kgdbts: config string too long\n");
-		return -ENOSPC;
+		return 1;
 	}
 	strcpy(config, opt);
-	return 0;
+	return 1;
 }
 
 __setup("kgdbts=", kgdbts_option_setup);