display: tool: add splash tool for generating logo file

Add logo_gen.py for generating splash log image, it converts
PNG file to image file proper for flashing splash partition.

Change-Id: I277c18d3352977c53b702d11698fec501ffede42
Merge "display: tool: add splash tool for generating logo file"
Merge dff982302e7706064fbb7b596be63c138a0cd15e on remote branch

Change-Id: I4a78d15716d8dc835f23c7e2829db176c09874fd
Merge "Merge dff982302e7706064fbb7b596be63c138a0cd15e on remote branch"
Merge f72b0c3fa157230308039b95976d1443abc4b8a6 on remote branch

Change-Id: I7203e0a9146396d0d59707f2c893571a8d19895b