mem-cache: Remove CacheSet.hh

mem-cache: Remove CacheSet.hh

Replacement policies aren't aware of cache sets and do not
organize blocks based on replacement data. Block search is
independent of block placement.

Besides, indexing policies have their own way of addressing
the sets, therefore there is no need to use this class anymore.

BlkType has been removed, as it wasn't being used.

Change-Id: Ia79c2a491e59f295c8d60a0466c317eb0e2bdab9
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/9782
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>