stm class: Hide STM-specific options if STM is disabled

If STM=n, it doesn't make sense to ask about STM_DUMMY and
STM_SOURCE_CONSOLE support, which are not even built when enabled
anyway. Hence hide these options if STM=n.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/stm/Kconfig

@@ -8,6 +8,8 @@ config STM
 
 	  Say Y here to enable System Trace Module device support.
 
+if STM
+
 config STM_DUMMY
 	tristate "Dummy STM driver"
 	help
@@ -24,3 +26,5 @@ config STM_SOURCE_CONSOLE
 
 	  If you want to send kernel console messages over STM devices,
 	  say Y.
+
+endif