microblaze: convert all simple headers to use asm-generic

All the simple microblaze header files were adapted to use their
asm-generic implementations. These files are more simple and were quite
straightforward to change.

fb.h, vga.h and parport.h previously did not exist, using
the generic version makes it possible to build more drivers
successfully in allyesonfig.

Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michal Simek <monstr@monstr.eu>