mem-cache: Add setters to validate and secure block

In order to allow polymorphism of the block these two
functions have been added, and all direct status
assignments to these bits have been substituted.

We also assert that the block has been invalidated
before insertion. Then the block is validated in
the insertion.

Change-Id: Ie7be42408721ad4c2c9dc880f82a62cb594f8668
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/14362
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Rename blk.cc/hh to cache_blk.cc/hh

Rename the files blk.cc and blk.hh to cache_blk.cc and cache_blk.hh
to comply with the usual file-class naming rules.

Change-Id: I8af45df3e4b8dd934fd9929ec914fb230cb2cb09
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/13416
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>