MAINTAINERS: update two greybus sections

Fix a file entry typo and drop the obsolete timesync entries, which were
all caught by:

	scripts/get_maintainer.pl --self-test=patterns

Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>