sdhci: orphan driver and list

Remove myself as maintainer from the sdhci driver and steer people
towards the new MMC list for discussing it.

Signed-off-by: Pierre Ossman <pierre@ossman.eu>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>