msm: mdss: generalize the hdcp 1.x registers programming

Create a register set for a given interface and make
hdcp state machine independent of the interface being
used to support multiple interfaces with different
register sets.

Change-Id: I62738697e91549fe44ef09b0a3aa905b37c00389
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>