msm: clk: hdmi: add support for atomic update

If required pixel clock is within the pll lock range,
update the pll without tear down to new pixel clock to
reduce the switching latency.

Change-Id: Iad54cd50aa419d3c1e3a2de40fbfd6feb5304bc8
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>