drm/i915/scaler: Fix WA_14011503117

This introduces and uses a variable id which is just uninitialized.
What really needs to be used is the scaler_id.

Fixes: 73309ed9 ("drm/i915/display: WA_14011503117")
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Nemesa Garg <nemesa.garg@intel.com>
Link: https://lore.kernel.org/r/20250806030856.3514127-1-suraj.kandpal@intel.com