MN10300: Default config choice GDBSTUB_TTYSM0 should be GDBSTUB_ON_TTYSM0

The configuration choice for the port on which the GDB stub listens has
a default of GDBSTUB_TTYSM0, but this should be GDBSTUB_ON_TTYSM0 to
match the option.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/mn10300/Kconfig.debug

@@ -101,7 +101,7 @@ config GDBSTUB_DEBUG_BREAKPOINT
 
 choice
 	prompt "GDB stub port"
-	default GDBSTUB_TTYSM0
+	default GDBSTUB_ON_TTYSM0
 	depends on GDBSTUB
 	help
 	  Select the serial port used for GDB-stub.