MN10300: Deprecate gdbstub

Deprecate the MN10300 arch's gdbstub in favour of KGDB, which is more capable
in some areas (such as SMP) and almost as capable in others (it's I/O is not as
decoupled and it can't start as early).  gdbstub will be removed in a later
version when we're satisfied with KGDB's working.
Signed-off-by: David Howells <dhowells@redhat.com>

arch/mn10300/Kconfig.debug

@@ -36,7 +36,7 @@ config KPROBES
 
 config GDBSTUB
 	bool "Remote GDB kernel debugging"
-	depends on DEBUG_KERNEL
+	depends on DEBUG_KERNEL && DEPRECATED
 	select DEBUG_INFO
 	select FRAME_POINTER
 	help
@@ -46,6 +46,9 @@ config GDBSTUB
 	  RAM to avoid excessive linking time. This is only useful for kernel
 	  hackers. If unsure, say N.
 
+	  This is deprecated in favour of KGDB and will be removed in a later
+	  version.
+
 config GDBSTUB_IMMEDIATE
 	bool "Break into GDB stub immediately"
 	depends on GDBSTUB