staging: comedi: me4000: Fixed code style issue

Fixed checkpatch.pl error message. Space prohibited before that ','

Signed-off-by: Marcus Hufvudsson <marcushuf@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>