dgrs: remove from build, config, and maintainer list

Stop building and configuring driver for Digi RightSwitch, which was
never actually sold to anyone, and remove it from MAINTAINERS.

In response to an investigation into the firmware of the "Digi Rightswitch"
driver, Andres Salomon discovered:
>
> Dear Andres:
>
> After further research, we found that this product was killed in place
> and never reached the market.  We would like to request that this not be
> included.

Since the product never reached market, clearly nobody is using this orphaned
driver.

Signed-off-by: Nathanael Nerode <neroden@gcc.gnu.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>