MAINTAINERS: update ARM pxa maintainers

Change pxa active maintainers, and remove more busy people.
Remove Eric's tree as it is not accessible anymore.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Daniel Mack <zonque@gmail.com>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Acked-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>