inputflinger: make parameter comment style consistent

The Google C++ style guide [0] suggests that parameter name comments
should be of the form `/*paramName=*/value`. This potentially allows
tooling to check that the parameter names are correct, too.

[0]: https://google.github.io/styleguide/cppguide.html#Function_Argument_Comments

Bug: none
Test: host-side inputflinger_tests
Change-Id: I89625844bcd19d27c43b4f14f1f207ade39a4718