msm: mdss: hdmi: Clear and disable interrupts when HDCP is inactive

When an HDCP interrupt is received while the HDCP session is
inactive, ensure that the interrupt it acknowledged and cleared
to avoid any potential interrupt storms.

Change-Id: Id297cb9a7d08a094727c966cf48966a6a37bb1f0
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>