base: create DPRINTF_UNCONDITIONAL

base: create DPRINTF_UNCONDITIONAL

This is similar to DPRINTFN, but it also prints a given flag to allow
communicating to users which flag enabled a given log.

This is useful for logs which are enabled with DTRACE instead of directly
with DPRINTF.

Change-Id: Ife2d2ea88aede1cdcb713f143340a8788a755b01
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22005
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Jason Lowe-Power <jason@lowepower.com>