lib/sysroot: fix placement for not-default deployment
lib/sysroot: fix placement for not-default deployment

When using the
OSTREE_SYSROOT_SIMPLE_WRITE_DEPLOYMENT_FLAGS_NOT_DEFAULT flag, the
deployment is said to be added after the booted or merge deployment.
Fix the condition to do so instead of adding it in the second place.

Closes: #1097
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree