ASoC: ti: j721e-evm: Check for not initialized parent_clk_id

During probe the parent_clk_id is set to -1 which should not be used to
array index within hsdiv_rates[].

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20210717122820.1467-3-peter.ujfalusi@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>