drm/amdgpu/nbio: improve code indentation and alignment

General code indentation and alignment changes such as replace spaces
by tabs or align function arguments as per the coding style
guidelines. Issue reported by checkpatch script.

Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
