drm/amdkfd: Fix indentation on switch statement

Cases should be same indentation as switch. Also fix string spanning
across multiple lines.

Signed-off-by: Graham Sider <Graham.Sider@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>