kernel-hacking: create submenu for arch special debugging options

The arch special options are a little long, so create a submenu for
them.

Link: http://lkml.kernel.org/r/20190909144453.3520-3-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -2158,8 +2158,12 @@ config IO_STRICT_DEVMEM
 
 	  If in doubt, say Y.
 
+menu "$(SRCARCH) Debugging"
+
 source "arch/$(SRCARCH)/Kconfig.debug"
 
+endmenu
+
 config HYPERV_TESTING
 	bool "Microsoft Hyper-V driver testing"
 	default n