MAINTAINERS: update maintainership of LTP

Also remove sf.net git repo which is no longer available and update link
to LTP web pages.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>