msm: mdss: dsi: ensure phy config is done only during power up

DSI phy reset and initialization should only be done when as part of
the power up sequence. This can happen at two different places:
    (1) During bootup or resume sequence
    (2) When exiting idle power collapse in static screen

The checks in the current implementation to ensure the above make use
of the panel blank status. However, it is possible that the DSI clocks
can be toggled even after panel has been blanked. This may result in phy
init sequence getting called resulting in spurious transitions on the
DSI lanes. Fix this issue by modifying the existing sequence
appropriately.

Change-Id: I1f67b24058b3c98fb4472867c0421ae47fdcd9c7
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>