ASoC: codecs: pcm3168a: Fix and updates for power management

Cezary Rojewski <cezary.rojewski@intel.com> says:

Set of changes composed of one fix and two improvements.

The fix leads the series and addresses "unbalanced disables" coming from
the regulator core during S4 (hibernation) scenario.

The SLEEP_PM_OPS are unset for the driver.  Hibernation (S4) causes no
resume (skipped thanks to smart_suspend=true) yet still performs the
suspend sequence unconditionally, see device_complete() in
drivers/base/power/main.c.  In essence, we end up with double suspend
(double disable) and thus the warning.  Exemplary stack:

unbalanced disables for regulator-dummy
WARNING: drivers/regulator/core.c:3244 at _regulator_disable+0x161/0x270, CPU#6: kworker/u64:2/120
(...)
Workqueue: pm pm_runtime_work
RIP: 0010:_regulator_disable+0x161/0x270
(...)
Call Trace:
  <TASK>
  regulator_bulk_disable+0xe4/0x220
  ? __pfx_regulator_bulk_disable+0x10/0x10
  ? pick_next_task_fair+0x36f/0x11f0
  ? __pfx_regmap_unlock_mutex+0x10/0x10
  ? regmap_unlock_mutex+0xe/0x20
  pcm3168a_rt_suspend+0x57/0x90 [snd_soc_pcm3168a]
  ? __pfx_pcm3168a_rt_suspend+0x10/0x10 [snd_soc_pcm3168a]
  __rpm_callback+0x69/0x200
  ? __pfx_pcm3168a_rt_suspend+0x10/0x10 [snd_soc_pcm3168a]
  rpm_callback+0xbc/0xd0
  rpm_suspend+0x225/0x960
  ? __pfx_rpm_suspend+0x10/0x10
  ? __kasan_check_write+0x14/0x20
  ? _raw_spin_lock_irq+0x8d/0xe0
  ? __pfx__raw_spin_lock_irq+0x10/0x10
  ? pwq_dec_nr_in_flight+0x63/0x4f0
  pm_runtime_work+0xd0/0xf0

In regard to the improvements, both aim to drop redundant operations.
One targets pm_runtime_idle() - no need to fire it manually,
device-driver core will do that for us - while the second replaces
preprocessor directive with pm_runtime_status_suspended() check.
No !CONFIG_PM dependency equals better code coverege with default
kconfigs.

Link: https://patch.msgid.link/20260525201801.1336936-1-cezary.rojewski@intel.com