Disable SIMD16 drop heuristics for XE3

Disable heuristics due to regression.

Author: stefan-il

IGC/common/igc_flags.h

@@ -1531,7 +1531,8 @@ DECLARE_IGC_REGKEY(bool, EnableReusingXYZWStoreConstPayload, true, "Enable reusi
 DECLARE_IGC_REGKEY(bool, EnableReusingLSCStoreConstPayload, false, "Enable reusing LSC stores const payload", false)
 DECLARE_IGC_REGKEY(bool, AllowSIMD16DropForXE2, true, "Controls the switch for XE2 simd16 drop", false)
 DECLARE_IGC_REGKEY(bool, AllowSIMD16DropForXE3, true, "Controls the switch for XE3 simd16 drop", false)
-DECLARE_IGC_REGKEY(bool, AllowEarlySIMD16DropForXE3, true, "Controls the early drop to simd16 for XE3", false)
+DECLARE_IGC_REGKEY(bool, AllowEarlySIMD16DropForXE3, false,
+                   "Controls the early drop to simd16 for XE3", false)
 DECLARE_IGC_REGKEY(DWORD, EarlySIMD16DropForXE3Threshold, 190, "Threshold for the early drop to simd16 for XE3", false)
 DECLARE_IGC_REGKEY(DWORD, RegPressureVerbocity, 2, "Different printing types", false)
 DECLARE_IGC_REGKEY(DWORD, RetryRevertExcessiveSpillingKernelThreshold, 10000,