mem-cache: Optimize sector valid and secure check

mem-cache: Optimize sector valid and secure check

Previously a loop was being done to check whether the
block was valid/secure or not. Variables have been
added to skip this loop and save and update sector
block state when sub-blocks are validated, invalidated
and secured.

Change-Id: Ie1734f7dfda9698c7bf22a1fcbfc47ffb9239cea
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/14363
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>