ASoC: msm: Fix for a seekbar issue during audio playback.

Issue is that when seek happens several times during audio playback,
and at some point last buffer write done event from DSP is received,
an ioctl drain is issued, which will set pending_buffer flag to 0,
In the mean time before drain finishes a seek comes, which issues
a flush on all the buffers and try to resume the playback again.
Now because the pending_buffer flag is set to 0, CMD_RUN will return
without any further writes to DSP. As a result no audio buffers are
reaching the DSP and hence no audio is getting played.
Make a fix is to set pending_buffer flag to 1 whenever playback is resumed
after seek.

Change-Id: I89812332f14e0682be28445ad1f15564f129ae11
Signed-off-by: Mingming Yin <mingming@codeaurora.org>

Conflicts:

	sound/soc/msm/msm-pcm-lpa.c
block/deadline: tweaked for better performance on android