Staging: comedi: addi-data: don't initialize a static variable to 0

In hwdrv_apci1564.c, one static variable is zero initialized.  This is
unneeded and redundant, so we remove the initialization.

Signed-off-by: Chase Southwood <chase.southwood@yahoo.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>