[PATCH] fbdev: imsttfb: Driver cleanups

- remove unneeded casts

- the pseudo_palette, if using the generic drawing functions, must always be
  u32 regardless of the bpp

- use framebuffer_alloc/framebuffer_release to allocate memory

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>