msm: pil: Implement tzapps support as a platform driver

Create a platform driver to manage the tzapps support instead of
having a module that exists for any 8660 device. This allows us
to add platform devices when the configuration actually supports
it and have pil_get() fail otherwise.

Change-Id: I22707d8947ef360522edb1cd9ee6792cbd8fe797
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>