MAINTAINERS: OMAP: hwmod: update hwmod code, data maintainership

Add myself and Benoît as co-maintainers of the OMAP hwmod core code.
(The OMAP hwmod code manages the integration of IP blocks on the OMAP SoC
family.)

Add Benoît as the maintainer of OMAP4-based SoC hwmod mode.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Benoît Cousson <b-cousson@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>