misc: Remove the FreeBSD namespace

This namespace has gone through the deprecation period
and can now be removed.

Change-Id: Ic0c838709121278584a295ea19a8283d5765b9c9
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/67365
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/generic/freebsd/threadinfo.hh

@@ -39,7 +39,6 @@
 namespace gem5
 {
 
-GEM5_DEPRECATED_NAMESPACE(FreeBSD, free_bsd);
 namespace free_bsd
 {
 

src/kern/freebsd/events.cc

@@ -44,7 +44,6 @@
 namespace gem5
 {
 
-GEM5_DEPRECATED_NAMESPACE(FreeBSD, free_bsd);
 namespace free_bsd
 {
 

src/kern/freebsd/events.hh

@@ -40,7 +40,6 @@
 namespace gem5
 {
 
-GEM5_DEPRECATED_NAMESPACE(FreeBSD, free_bsd);
 namespace free_bsd
 {