misc: Collapse all uses of DTRACE(x) to Debug::x.

Also mark the DTRACE macro as deprecated.

Change-Id: I99d9a9544b539117b375186e3e425d73d3c5cab7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45009
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

src/cpu/base.cc

@@ -579,7 +579,7 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
         /* This code no longer works since the zero register (e.g.,
          * r31 on Alpha) doesn't necessarily contain zero at this
          * point.
-           if (DTRACE(Context))
+           if (Debug::Context)
             ThreadContext::compare(oldTC, newTC);
         */