MAINTAINERS: update entry for TMIO MMC driver

I have some more additions planned for this driver, so I'd like to get
notified of other changes and coordinate them. Drop Ian as maintainer
because he hasn't been involved in development for a while. Thanks for
all the initial work, of course! Also, reflect the recent changes to
the include file layout.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Ian Molton <ian@mnementh.co.uk>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>