iscsitarget: list previous config file location as a %ghost file

This update fixes the following issue with iscsitarget:
- bnc#801469: updated spec file to list previous config file location as a %ghost file

Fixed bugs
bnc#801469
iscsitarget: upgrading from 12.1 to 12.2 replaces ietd.conf with a generic sample, old file is saved as ietd.conf.rpmsave
Selected Binaries
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