checkpatch: additional MAINTAINER section entry ordering checks

checkpatch: additional MAINTAINER section entry ordering checks

There is a preferred order for the entries in MAINTAINERS sections.

See commits 3b50142d8528 ("MAINTAINERS: sort field names for all
entries") and 6680125ea5a2 ("MAINTAINERS: list the section entries in
the preferred order")

Add checkpatch tests to try to keep that ordering.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: http://lkml.kernel.org/r/17677130b3ca62d79817e6a22546bad39d7e81b4.camel@perches.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>