drm/amdgpu: Fix macro name _AMDGPU_TRACE_H_ in preprocessor if condition

Add an underscore in amdgpu_trace.h line 24 "_AMDGPU_TRACE_H".

Fixes: d38ceaf9 ("drm/amdgpu: add core driver (v4)")
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Chenyang Li <lichenyang@loongson.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>