HSD #14010901465-2: Backport Frame Buffer II driver from 4.14-ltsi

commit  cc0a925178faa53e34cb15c82e41a0e65f1dc415 from
https://github.com/altera-opensource/linux-socfpga.git



Because of commit("deb00d27 fbdev: make unregister/unlink
functions not fail"), the function unregister_framebuffer changed
from returning int to just a void.

Signed-off-by: Dinh Nguyen <dinh.nguyen@intel.com>
Signed-off-by: Meng Li <Meng.Li@windriver.com>