cpu: Fix style and add overrides to bas_dyn_inst.hh.

cpu: Fix style and add overrides to bas_dyn_inst.hh.

Either return types, brackets and the function body should all be on
their own line, or the entire function should be on a single line.

Consistently place the * or & up against the variable name and not the
type name. There isn't an official rule for which to use, but the
majority of existing uses were this way.

Add overrides for overridden virtual methods.

These fixes get rid of compiler warnings which are breaking the build
for me.

Change-Id: Ifc6ace4794a66ffd031ee686f6b6ef888004d786
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34216
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>