fix framebuffer driver
Take care of FIXME based on https://www.kernel.org/doc/Documentation/fb/api.txt
change so that vmem is standard pixel buffer and use delayed work to improve performance
Merge branch 'framebuffer' of https://github.com/dlech/ev3dev-kernel into dlech-framebuffer
Merge branch 'dlech-framebuffer'
Merged in dlech's suggested changes for the ST7586S framebuffer driver