[llvm] [NFC][SPIRV] remove unimplemented function define for `selectCross` (PR #134478)

[Farzon Lotfi via llvm-commits]

https://github.com/farzonl created https://github.com/llvm/llvm-project/pull/134478

-`selectCross` looks to be a function that had its implementation and usage removed but this define some how stuck around.
- this change removes the definition.

>From bd207f811b6f9b3aefae960a25dcfc1bf8c58608 Mon Sep 17 00:00:00 2001
From: Farzon Lotfi <farzonlotfi at microsoft.com>
Date: Fri, 4 Apr 2025 23:42:02 -0400
Subject: [PATCH] [NFC][SPIRV] remove unimplemented function header

---
 llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp | 2 --
 1 file changed, 2 deletions(-)

diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 946a295c2df25..662c38ca4ed28 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -183,8 +183,6 @@ class SPIRVInstructionSelector : public InstructionSelector {
 
   bool selectCmp(Register ResVReg, const SPIRVType *ResType,
                  unsigned comparisonOpcode, MachineInstr &I) const;
-  bool selectCross(Register ResVReg, const SPIRVType *ResType,
-                   MachineInstr &I) const;
   bool selectDiscard(Register ResVReg, const SPIRVType *ResType,
                      MachineInstr &I) const;