Config creation script creates empty configs for RHEL when Fedora has turned on a dep

We have seen these empty config MRs opened before, but I just verified the cause. Today I trued up the first round 5.12 config options for Fedora, moving things from pending to fedora and setting them appropriately. A few of those were menu options and rather than dig through the whole Kconfig trees, I got lazy and just ran a merge job to have the script create pending-fedora entries for each of the new config items exposed by my flipping a config from off to on. When it does this, the config item is not missing for RHEL, but it creates a RHEL entry anyway, and since there is no default, and the config is not actually missing from RHEL, the MR is just empty files in pending-common. We need to fix up the script to handle the common case where Fedora needs something set/reviewed and RHEL does not because the dep isn't there.