drm/msm/dsi: Delay dsi_clk_init

Initialize clocks only after we get the DSI host version. This will allow
us to get clocks using a pre-defined list based on the DSI major/minor
version of the host. This is required since clock requirements of
different major DSI revisions(v2 vs 6g) aren't the same.

Modify dsi_get_version to get the interface clock, and then put it after
it is used.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>