MAINTAINERS: correct entry for legacy RTC-driver

Because no one dared to remove it so far, let's keep the entry correct, at
least.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>