nat/vty: Convert into str for the VTY command

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ERROR: testBSCreload (__main__.TestVTYNAT)
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Traceback (most recent call last):
  File "./vty_test_runner.py", line 656, in testBSCreload
    nat_msc_ip(self, ip, port)
  File "./vty_test_runner.py", line 1096, in nat_msc_ip
    x.vty.command("msc port " + port)
TypeError: cannot concatenate 'str' and 'int' objects

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1 file changed
tree: 77b4c201cb449708be2078b799f9f695f6c38916
  1. contrib/
  2. debian/
  3. openbsc/
  4. .gitignore