[Coverity CID :190960]Various in /tests/subsys/fs/fcb/src/fcb_test_last_of_n.c

[mandarcthorat1]

Static code scan issues seen in File: /tests/subsys/fs/fcb/src/fcb_test_last_of_n.c
Category: Various
Function: fcb_test_last_of_n
Component: Tests
CID: 190960
Please fix or provide comments to square it off in coverity in the link: https://scan9.coverity.com/reports.htm#v32951/p12996

[varun-sha]

Its false positive, all entries are getting assigned in for loop before being used