arm/dt: msm9625: Add mmio architected timer node

Add the memory mapped architected timer node along side the
previous version of the binding. This allows us to transition to
the new node without putting the binding and code change together
in the same commit.

Change-Id: I289f8ceb72a747f2f9585f053d3e8c5280c79967
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>