ASoC: test-component: Support continuous rates for test component

There's no reason to limit the supported rates of the test component
to specific ones as if it's a real piece of hardware. Set the rates to
continuous to aid in testing different rates.

Signed-off-by: John Watts <contact@jookia.org>
Link: https://patch.msgid.link/20241112-alsa_test_rates-v1-1-95cf529db871@jookia.org


Signed-off-by: Mark Brown <broonie@kernel.org>