Move I2C driver model init earlier in the boot sequence

This avoids oopsing in statically linked systems when some
subsystems register I2C drivers in subsys_initcall() code,
but those subsystems are linked (and initialized) before I2C.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>