Fix Fibre Channel attach for single WWN

The code allowed for only a string of the WWN or a list of them.
Unfortunately unicode is also returned, for which the attach fails.
This patch allows for unicode as well.

Change-Id: I1d81abc3f8569ce8b3fb25c0e9c8aefd10e9aae8
Fixes: bug 1214413
Merge "Fix Fibre Channel attach for single WWN"