ALSA: emu10k1: Use managed buffer allocation

Clean up the driver with the new managed buffer allocation API.
The normal playback streams need a workaround for the aligned buffer,
and cannot apply the straight snd_pcm_lib_malloc() stuff, so they
remain untouched, while other streams are converted to the new managed
mode.

Most of hw_params and hw_free callbacks became superfluous and got
dropped.

Link: https://lore.kernel.org/r/20191209094943.14984-37-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>