media: video: VC ISR restructure to make code more readable

As new features were added to VCAP the ISR for VC has become
increasingly complex and difficult to read. It was determined that
the VC ISR code should be simplified and cleaned up in order to
make the code flow more easier to read.

Change-Id: If7bc0a41e14c40f67120dacde9a1544e8f1ef7b1
Signed-off-by: Terence Hampson <thampson@codeaurora.org>