msm: mdss: Add suspend resume support in HDMI Tx controller

For primary display panels, usually power off/on during suspend/resume
should suffice. But for external display panels like HDMI TVs,
there is an additional hw circuitry for hot-plug detect which also
needs to be turned off/on based on the state when suspend/resume is
initiated. This change adds such support in HDMI Tx driver.

CRs-Fixed: 413722
Change-Id: I7640d13c08f86f1ae0ae13cb2d1411f0354ca3fe
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>