kconfig: do not use OR-assignment for zero-cleared structure

The simple assignment is enough because memset() three lines above
has zero-cleared the structure.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/symbol.c

@@ -831,7 +831,7 @@ struct symbol *sym_lookup(const char *name, int flags)
 	memset(symbol, 0, sizeof(*symbol));
 	symbol->name = new_name;
 	symbol->type = S_UNKNOWN;
-	symbol->flags |= flags;
+	symbol->flags = flags;
 
 	symbol->next = symbol_hash[hash];
 	symbol_hash[hash] = symbol;