i2c documentation fixes.

>From Hideki Iwamoto:
* i2c_smbus_read_i2c_block_data is not deleted in 2.6.10. It still
  exists.
* The name which can be set to i2c_driver is up to 31 characters.

>From Jean Delvare:
* Reword the paragraph about i2c_driver.name, to reflect the "new"
  naming policy.
* Delete the out-of-date note about now gone inc_use and dec_use
  fields.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>