msm: mdss: support danger safe signal per pipe

MDPv1.5 and MDPv1.8 has danger safe LUTs and control setting
register under MDP register space. These LUTs and control
settings can be different for each pipe for MDPv1.7. It makes
"panic-ctrl-offsets" configuration also optional for VIG, RGB
and DMA pipes. This change handles the danger safe signal
programming for such MDP version.

Change-Id: Icf0e4a732d7372493d1166579b90a7c2df7ae126
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>