disp: msm: dp: fix dp_display module's state handling

Currently the DP display's states are not able to handle
the use cases like suspend/resume. The required steps of
host initialization and ready are not properly followed
in such cases. Define proper DP display states, set and
unset at the right places to make sure dp is in proper
state in such cases.

Change-Id: Ibf6d35dec3ab373a7225b30ac1c2f9864bb6ff78
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>