mem-cache: Encapsulate CacheBlk's status

mem-cache: Encapsulate CacheBlk's status

Encapsulate this variable to facilitate polymorphism.

- The status enum was renamed to CoherenceBits, since it
  lists the coherence bits supported by the CacheBlk.
- status was made protected and renamed to coherence since
  it contains the coherence bits.
- Functions to set, clear and get the coherence bits were
  created.
- To set a status bit, the block must be validated first.
  This guarantees a constant flow and helps catching bugs.

As a side effect, some of the modified files contained long
lines, which had to be split.

Change-Id: I558cc51ac685d30b6bf298c78f86a6e24ff06973
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34960
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>