ENGR00171536 HDMI handle mmapped audio buffers

ENGR00171536 HDMI handle mmapped audio buffers

The ALSA userspace requires mmapped buffer access to support sample
rate conversion.

Our hardware requires the driver to add frame information to the pcm
data.  For non-mmap access, the snd_pcm_ops' copy routine will do it.
For mmap access, we have to do it in the isr.  This is not ideal, but
it will work.

Signed-off-by: Alan Tull <r80115@freescale.com>