drm/amdgpu/atomfirmware: Clean up errors in amdgpu_atomfirmware.c

Fix the following errors reported by checkpatch:

ERROR: spaces required around that '>=' (ctx:WxV)
ERROR: spaces required around that '!=' (ctx:WxV)
ERROR: code indent should use tabs where possible

Signed-off-by: Ran Sun <sunran001@208suo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>