msm: mpq8064: VCAP corner case bug fixes

Closing VCAP devices could be called without calling stream off:
This problem would make VCAP resources taken by devices no longer
running.

Using unsigned variable to store signed result: This problem would
allow stream on to continue even when function returned error.

Fix problem of reading VP irq status register too early: It was
possible for cadence detection bit to be propgated faster by only
a few clock cycles then the picture done bit. When the irq status
read was performed and by the time a write to the clear register
was performed the picture done bit would propgate. Since the irq
is rising edge triggered this would cause a problem and the irq
would not be triggered until VP was reset.

Remove unused code

Change-Id: Iba72354c06287efb27178edf64d8d3f459dbf954
Signed-off-by: Terence Hampson <thampson@codeaurora.org>