msm: mdss: hdmi: check clk state before power on

Clocks should be enabled and running at proper rates before
powering on hdmi transmitter. In fast plug in/plug out of
hdmi cable cases or fast suspend resume cases, there can be
a race condition related to enable/disable of clocks and
hdmi power on/off. Make sure, in such corner cases, hdmi
transmitter core is not being programmed to avoid any
possible un-clocked register access issue.

Change-Id: Ide3db0d0947f4bb5deee26aee95111be27523924
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>