Merge branch 'netdevsim-fib-route-delete-leak'

Ido Schimmel says:

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netdevsim: fib: Fix reference count leak on route deletion failure

Fix a recently reported netdevsim bug found using syzkaller.

Patch #1 fixes the bug.

Patch #2 adds a debugfs knob to allow us to test the fix.

Patch #3 adds test cases.
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Signed-off-by: David S. Miller <davem@davemloft.net>