Remove the term 'syspanel' from docs

Since the refactorization of syspanel occurred at
the very early Folsom days, the docs should reflect this too.

Cherry-picked from I8539b0b8bda2f63366c6de75b1a010f52f07fd0e

Fixes bug 1179873

Change-Id: I890c41048ad2cb9f44a1dacce01c570746ce27db