monarudo: update display boardfile

* enable splash screen and set splash_screen_size
* reduce minimum brightness

Change-Id: I6f321d585e9ef428f62139c2c678b12fbb22f900
monarudo: add missing dsi_pll regulator supply

Originally introduced in patch ID:
  fb4e77edf9ce62aa836e8406aa9dfc1bf9aecab5
  "msm: display: Add DSI clock control for MDP GDHS power collapse"

Change-Id: Iead0032bb7d157376166e1a9c564095c373fe79b