MAINTAINERS: add maintainer for OMAP hwmod data

I wind up reviewing and committing most of the OMAP hwmod data
patches, so, add myself to MAINTAINERS there so folks will cc me.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Benoît Cousson <bcousson@baylibre.com>