kconfig: remove redundant assignment prompt = prompt

Semi-automatic removing of localization macros changed the line
from "prompt = _(prompt);" to "prompt = prompt;". Drop the
reduntand assignment.

Fixes: 694c49a7c0 ("kconfig: drop localization support")
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/nconf.c

@@ -755,7 +755,6 @@ static void build_conf(struct menu *menu)
 			switch (ptype) {
 			case P_MENU:
 				child_count++;
-				prompt = prompt;
 				if (single_menu_mode) {
 					item_make(menu, 'm',
 						"%s%*c%s",