kconfig/nconf: remove useless conditionnal

After the test

	if (!submenu || ...)
		continue;

the variable `submenu' can _not_ be NULL, so do not test for this
situation.

Cc: Nir Tzachar <nir.tzachar@gmail.com>
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/kconfig/nconf.c

@@ -1153,10 +1153,7 @@ static void conf(struct menu *menu)
 		submenu = (struct menu *) item_data();
 		if (!submenu || !menu_is_visible(submenu))
 			continue;
-		if (submenu)
 		sym = submenu->sym;
-		else
-			sym = NULL;
 
 		switch (res) {
 		case ' ':