drm/amdgpu: clean up some inconsistent indentings

drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:65 amdgpu_gem_fault() warn: inconsistent indenting

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3639Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NYang Li <yang.lee@linux.alibaba.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>