ARM: OMAP: Use I2C bus registration helper

ARM: OMAP: Use I2C bus registration helper

This patch starts using introduced I2C bus registration helper by cleaning
up registration currently done in various places and by doing necessary
board file modifications.

Patch modifies those board files that are merged upstream. Most of the
boards except osk and 2430sdp are configured to use 100 kHz I2C clock
until they are verified for higher clock.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>