msm: pp2s: FSM9900 PP2S driver

Adding pp2s notification driver.  This driver is required, for two
reasons:
  1) So that interested applications can be informed of PP2S (Pulse
     Per 2 Second) interrupts, and
  2) So that the wall clock time registers can be
     accessed/manipulated

Change-Id: I9d81ef3622743ff03bef6848f007a65e3dda2298
Acked-by: Perry Randise <prandise@qti.qualcomm.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>