drm/amdgpu: make trace format uniform csv name=value

Most of the traces have uniform format except for two of them. Having
all the traces match makes it simple to run awk on the ftrace output.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>