The current cursor interface is confusing.  Some fields are taken from the
cursor structure in struct fb_info (enable, mask, rop fields) and the rest are
taken from the passed cursor structure.  These lead to a lot of confusion,
making it hard for developers to write their own implementation.

Also, the cursor code has several 'short-circuits', occassionally leading to
undefined cursor behavior.

These are the changes brought about by the patch:

- Removed struct fb_cursor and related fields from struct fb_info, and
  instead, placed them in a struct not visible to fbdev.

- The struct fb_cursor passed to fb_cursor() will _always_ contain valid
  data with various bitflags indicating which fields have changed

- The struct fb_pixmap sprite in struct fb_info is used only by drivers with
  hardware cursor implementation.  Initializing and allocating memory for this
  structure is not needed.  Remove initialization and memory allocation.

- The FBIO_CURSOR ioctl is broken (because fb_cursor() is broken).  For now,
  remove fb_cursor code and make the FBIO_CURSOR ioctl always return -ENODEV.

- The flag FB_CUR_SETCUR is changed to FB_CUR_SETIMAGE, indicating that the
  cursor sprite has changed.  The image change is now checked by fbcon so
  drivers will not unnecessarily load the sprite image everytime.  This causes
  hardware cursors to flicker, especially in rivafb.

- Remove fb_load_cursor_image().  This is unused, and should not be
  implemented generically.

- Documented the usage of the cursor interface in skeletonfb.c
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>