[samsung-i9070] Add framebuffer mode in initfs-hook

After various tests we finally discovered that the framebuffer mode have to be set otherwise the osk-sdl initialized the framebuffer with a wrong memory size and doesn't work.

Even the order of the framebuffer settings matters, if the cat ..modes > ..mode is placed before the bits_per_pixel and the virtual_size, it doesn't work correctly.

(Here a small utility used to do the investigations)