ASoC: fsl_ssi: Add suspend/resume support

Doing a suspend/resume sequence while playing an audio track in the backgroung
causes broken audio right after resume:

root@freescale /$ aplay clarinet.wav &

root@freescale /home$ Playing WAVE 'clarinet.wav' : Signed 16 bit Little Endian,
 Rate 44100 Hz, Mono

root@freescale /home$ echo mem > /sys/power/state
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.002 seconds) done.
Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done.
Suspending console(s) (use no_console_suspend to debug)
PM: suspend of devices complete after 37.082 msecs
PM: suspend devices took 0.040 seconds
PM: late suspend of devices complete after 4.234 msecs
PM: noirq suspend of devices complete after 4.618 msecs
Disabling non-boot CPUs ...
PM: noirq resume of devices complete after 4.013 msecs
PM: early resume of devices complete after 4.000 msecs
PM: resume of devices complete after 68.907 msecs
PM: resume devices took 0.070 seconds
Restarting tasks ... Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
Suspended. Trying resume. Failed. Restarting stream. Done.
....

Add SNDRV_PCM_TRIGGER_RESUME/SUSPEND cases so that we can gracefully handle
system suspend/resume.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>