Fix misspellings in neutron

Fix misspellings detected by:
* pip install misspellings
* git ls-files | grep -v locale | misspellings -f -

Change-Id: I93d9e2a65b0c1d1d801cae59b74d7258fbdb17dc
Closes-Bug: #1257295
Merge "Fix misspellings in neutron"