include: media: Invert naming of VCAP polarity

There was some misunderstanding regarding what polarity referred
to. It was originally assumed that positive pulse polarity referred
to the active low. This was incorrect and this patch fixes this
misunderstanding by inverting the naming fo VCAPs polarity.

CRs-Fixed: 420063
Change-Id: I90c02539962c105aaafcbf6d577648d6504b158e
Signed-off-by: Terence Hampson <thampson@codeaurora.org>