cirrusfb: remove typedefs

This patch replaces "typedef enum" with "enum type" constructs.  Using the
typedef is error for the checkpatch.pl script.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>