[PATCH] fbdev: Generic drawing function cleanups

  From Ulrich Eckhardt:

   * removed trailing whitespace
   * use helper function for common bitwise operations
   * fixed several cases where either the wrong mask was used for bitops
     or the mask was computed falsely, messing up <32 BPP support
   * added self-tests for bitcpy_rev() algorithm in module-init function
   * no need to use explicitly sized integers in some cases
   * added a few comments where things weren't obvious to me

  I tested these changes on an Au1100 based board, using the patches to its
  framebuffer code that were posted here by Christian Pellegrin[1]. I had this
  code working both on a 16BPP color LCD and a 4BPP monochrome one.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>