[Autobackout][FuncReg]Revert of change: 9f63791

 Turn on UseVMaskPredicate

Enable pixel shader interpolation improvement

Author: iwwu

IGC/common/igc_flags.h

@@ -426,8 +426,8 @@ DECLARE_IGC_REGKEY(bool, UseMTInLLD,                    false, "Use multi-thread
 DECLARE_IGC_REGKEY(bool, NoCatchAllDebugLine,           false, "Don't emit special placeholder instruction to map VISA orphan instructions", false)
 DECLARE_IGC_REGKEY(bool, EnableTestSplitI64,            false, "Test legalization that split i64 store unnecessarily, to be deleted once test is done[temp]", true)
 DECLARE_IGC_REGKEY(bool, ShaderDumpTranslationOnly,     false, "Dump LLVM IR right after translation from SPIRV to stderr and ignore all passes", false)
-DECLARE_IGC_REGKEY(bool, UseVMaskPredicate,             true,  "Use VMask as predicate for subspan usage (emitInterpolate)", false)
-DECLARE_IGC_REGKEY(bool, UseVMaskPredicateForLoads,     true,  "Use VMask as predicate for subspan usage (loads only)", true)
+DECLARE_IGC_REGKEY(bool, UseVMaskPredicate,             false, "Use VMask as predicate for subspan usage", false)
+DECLARE_IGC_REGKEY(bool, UseVMaskPredicateForLoads, true, "Use VMask as predicate for subspan usage (loads only)", true)
 DECLARE_IGC_REGKEY(bool, UseVMaskPredicateForIndirectMove, true, "Use VMask as predicate for subspan usage (indirect mov only)", true)
 DECLARE_IGC_REGKEY(bool, StackOverflowDetection,        false, "Inserts checks for stack overflow when stack calls are used.", true)
 DECLARE_IGC_REGKEY(bool, BufferBoundsChecking,          false, "Setting this to 1 (true) enables buffer bounds checking", false)