MAINTAINERS: List i2c-omap and i2c-davinci drivers

This will ensure that the right people and lists are notified when
these drivers are modified.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Tony Lindgren <tony@atomide.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@ti.com>