[PATCH] i810fb: Cleanup I2C code

- The functions for reading the 1st and 2nd bus are essentially the same,
  except for the register.  Consolidate them all.

- According to Nicolas Boichat, there is an undocumented 3rd i2c bus for
  attaching daughter cards.  Add support for this.

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