rv: Fix compilation if !CONFIG_RV_REACTORS

The kernel test robot spotted a compilation error if reactors are
disabled.

Fix the warning by keeping LTL monitor variable as always static.

Cc: Thomas Weißschuh <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Fixes: 4f739ed19d22 ("rv: Pass va_list to reactors")
Signed-off-by: Gabriele Monaco <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

include/rv/ltl_monitor.h

···
 #endif
 
 #define RV_MONITOR_NAME CONCATENATE(rv_, MONITOR_NAME)
-
-#ifdef CONFIG_RV_REACTORS
 static struct rv_monitor RV_MONITOR_NAME;
-#else
-extern struct rv_monitor RV_MONITOR_NAME;
-#endif
 
 static int ltl_monitor_slot = RV_PER_TASK_MONITOR_INIT;