mem-cache: Add more compression stats

Add stats to calculate the total number of compressions, decompressions
and the average compression size, in number of bits.

Change-Id: I5eb563856c1ff54216e1edcd2886332b7481cbfe
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22609
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
2 files changed