base: Rename Flag status to enabled

base: Rename Flag status to enabled

The semantic of "The status of a flag is true/false" may be
confusing. Rename `status` to `enabled`, so that queries
become "Is this flag enabled?".

Change-Id: I8cdd76766d80d65007a9f204abcf71b18211ab42
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/38711
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>