ALSA: pcm: use helper functions to refer parameters as constants

To fixup some parameters, ALSA PCM core refers the other parameters as
constants. There're some macros for this purpose.

This commit replaces codes with them.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>