staging/comedi/drivers/usbduxsigma.c: updated address details

Changed my e-mail address to mail@berndporr.me.uk. The old one
is no longer used.

Signed-off-by: Bernd Porr <mail@berndporr.me.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>