dist: ami: fix AMI_OPT receiving no value
dist: ami: fix AMI_OPT receiving no value

We assign AMI=0 and AMI_OPT=1, so in the true case, AMI_OPT has no value,
and a later compare fails.

avikivity/scylla,kjniemi/scylla,raphaelsc/scylla,kjniemi/scylla,kjniemi/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,raphaelsc/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,raphaelsc/scylla