dvbbasebin: don't rely on g_key_file_get_(integer|uint64) return when setting properties

Currently when setting int/uint params the dvbbasebin fails to parse params that have value 0, because it's checking if the return value from g_key_file_get_uint64 or g_key_file_get_integer is 0 and treating it as an error, but instead the code should pass an GError and check if that error is NULL or not to take decision if fails or not.