monkey: fix building with debugging symbols

Fix a typo in the monkey package - should be MONKEY_CONF_OPTS
instead of MONKEY_CONF_OPT.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/monkey/monkey.mk

@@ -47,7 +47,7 @@ MONKEY_POST_INSTALL_TARGET_HOOKS += MONKEY_REMOVE_DANGLING_SYMLINK
 endif
 
 ifeq ($(BR2_ENABLE_DEBUG),y)
-MONKEY_CONF_OPT += --debug
+MONKEY_CONF_OPTS += --debug
 endif
 
 define MONKEY_CONFIGURE_CMDS