ALSA: pcm: Fix sparse warnings wrt snd_pcm_state_t

Since we have a bitwise definition of snd_pcm_state_t and use it for
certain struct fields, a few new (and years old) sparse warnings came
up.  This patch is an attempt to cover them.

- The state fields in snd_pcm_mmap_status* and co are all defined as
  snd_pcm_state_t type now

- The PCM action callbacks take snd_pcm_state_t argument as well;
  some actions taking special values got the explicit cast and
  comments

- For the PCM action that doesn't need an extra argument receives
  ACTION_ARG_IGNORE instead of ambiguous 0

While we're at it, the boolean argument is also properly changed to
bool and true/false, as well as a slight refactoring of PCM pause
helper function to make easier to read.

No functional changes, just shutting up chatty sparse.

Fixes: 46b770f720 ("ALSA: uapi: Fix sparse warning")
Reported-by: kbuild test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20200131152214.11698-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/pcm.h

@@ -1450,7 +1450,7 @@ struct snd_pcm_status64 {
 #define SNDRV_PCM_IOCTL_STATUS_EXT64	_IOWR('A', 0x24, struct snd_pcm_status64)
 
 struct snd_pcm_status32 {
-	s32 state;		/* stream state */
+	snd_pcm_state_t state;		/* stream state */
 	s32 trigger_tstamp_sec;	/* time when stream was started/stopped/paused */
 	s32 trigger_tstamp_nsec;
 	s32 tstamp_sec;		/* reference timestamp */
@@ -1461,7 +1461,7 @@ struct snd_pcm_status32 {
 	u32 avail;		/* number of frames available */
 	u32 avail_max;		/* max frames available on hw since last status */
 	u32 overrange;		/* count of ADC (capture) overrange detections from last status */
-	s32 suspended_state;	/* suspended stream state */
+	snd_pcm_state_t suspended_state;	/* suspended stream state */
 	u32 audio_tstamp_data;	/* needed for 64-bit alignment, used for configs/report to/from userspace */
 	s32 audio_tstamp_sec;	/* sample counter, wall clock, PHC or on-demand sync'ed */
 	s32 audio_tstamp_nsec;