msm: mdss: Clean-up hpd debouncing logic of HDMI Tx controller

Implement hot-plug detect (HPD) software debouncing by
disabling the HPD interrupt until we finish processing
a previous HPD interrupt.

Change-Id: I434a223a3d340d5759346e071d5350d412de2c20
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>