drm/i915/tgl: Add note about Wa_1607063988

This issue workaround in Wa_1607063988 has the same fix as
Wa_1607138336, so just adding a note in the code.
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227220101.321671-6-jose.souza@intel.com

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -1333,7 +1333,10 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
 			     GEN9_CS_DEBUG_MODE1,
 			     FF_DOP_CLOCK_GATE_DISABLE);
 
-		/* Wa_1607138336:tgl */
+		/*
+		 * Wa_1607138336:tgl
+		 * Wa_1607063988:tgl
+		 */
 		wa_write_or(wal,
 			    GEN9_CTX_PREEMPT_REG,
 			    GEN12_DISABLE_POSH_BUSY_FF_DOP_CG);