kconfig: remember the current choice while parsing the choice block

Instead of the boolean flag, it will be more useful to remember the
current choice being parsed.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/parser.y

@@ -28,9 +28,7 @@ static void zconf_error(const char *err, ...);
 static bool zconf_endtoken(const char *tokenname,
 			   const char *expected_tokenname);
 
-struct menu *current_menu, *current_entry;
-
-static bool inside_choice = false;
+struct menu *current_menu, *current_entry, *current_choice;
 
 %}
 
@@ -147,7 +145,7 @@ config_entry_start: T_CONFIG nonconst_symbol T_EOL
 
 config_stmt: config_entry_start config_option_list
 {
-	if (inside_choice) {
+	if (current_choice) {
 		if (!current_entry->prompt) {
 			fprintf(stderr, "%s:%d: error: choice member must have a prompt\n",
 				current_entry->filename, current_entry->lineno);
@@ -256,12 +254,12 @@ choice_entry: choice choice_option_list
 
 	$$ = menu_add_menu();
 
-	inside_choice = true;
+	current_choice = current_entry;
 };
 
 choice_end: end
 {
-	inside_choice = false;
+	current_choice = NULL;
 
 	if (zconf_endtoken($1, "choice")) {
 		menu_end_menu();