i2c/tps65010: New-style driver updates, part 1

Prepare to convert tps65010 driver to "new style" driver by changing
how it references the i2c_client.  This lets the eventual patch with
driver and platform updates be smaller.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>