arch,kern: Rename some function events to have better names.

arch,kern: Rename some function events to have better names.

Rename many of the Event classes to have more succinct or
consistent names, and fix various style issues.

Change-Id: Ib322da31d81e7a245a00d21786c2aa417c9f2cde
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26703
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>