msm: mdss: hdmi: Fix HDCP ddc clean up wait time

With existing implementation the check for ddc hardware
not ready always fails because of incorrect logic and
driver always waits for 2 seconds even if there is no
pending hardware ddc transaction. Fix this by waiting
only for the time ddc transactions are underway.

Change-Id: Ic8396200d5d078d604ba3b4414d41644b455c103
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>