kconfig: Invalidate all symbols after changing to y or m.

Since commit 89b90609 ("kconfig: Add yes2modconfig and
mod2yesconfig targets.") forgot to clear SYMBOL_VALID bit after
changing to y or m, these targets did not save the changes.
Call sym_clear_all_valid() so that all symbols are revalidated.

Fixes: 89b90609 ("kconfig: Add yes2modconfig and mod2yesconfig targets.")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/confdata.c

@@ -1331,9 +1331,8 @@ void conf_rewrite_mod_or_yes(enum conf_def_mode mode)
 
 	for_all_symbols(i, sym) {
 		if (sym_get_type(sym) == S_TRISTATE &&
-		    sym->def[S_DEF_USER].tri == old_val) {
+		    sym->def[S_DEF_USER].tri == old_val)
 			sym->def[S_DEF_USER].tri = new_val;
-			sym_add_change_count(1);
-		}
 	}
+	sym_clear_all_valid();
 }