sim: Stop using DPRINTF_UNCONDITIONAL in the event class.
sim: Stop using DPRINTF_UNCONDITIONAL in the event class.

Just because the current methods of the base class only call
Event::trace from within DTRACE(Event), that's no guarantee that future
methods will, that the call sites won't be changed so that they don't,
or any number of subclasses that may not even exist today will.

Instead, we should incur the very slight overhead of checking the
Debug::Event variable again to ensure expected behavior, and to avoid
unnecessary complexity for a very small optimization when we're already
enabled a high overhead behavior like tracing for all events in a
virtual function.

Change-Id: I1c360b2ba73ad73c0658e85e9122f1fef07f93ce
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/44986
Reviewed-by: Daniel Carvalho <91779fc734d358d9575ec4910de29bfcbcaf1b22@yahoo.com.br>
Maintainer: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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