staging: comedi: vmk80xx: fix compiler warning

staging: comedi: vmk80xx: fix compiler warning

commit 13f7952f8f13fb1bbd18b85988e3a5bbbed00879 upstream.

gcc complains about some potentially uninitalized variables here, yet it
can not happen, due to an enumerated type (either the board is one type
or the other.)  Make the compiler happy by providing a default case
option that makes the logic a bit simpler for it to determine that there
really isn't a problem here.

Cc: H Hartley Sweeten <hartleys@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>