ALSA: pcm: Add a standalone version of snd_pcm_limit_hw_rates

ALSA: pcm: Add a standalone version of snd_pcm_limit_hw_rates

It can be useful to derive min/max rates of a snd_pcm_hardware without
having a snd_pcm_runtime, such as before constructing an ASoC DAI link.

Create a new helper that takes a pointer to a snd_pcm_hardware directly,
and refactor the original function as a wrapper around it, to avoid
needing to update any call sites.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200305051143.60691-2-samuel@sholland.org
Signed-off-by: Mark Brown <broonie@kernel.org>