[mlir][ArmSME][NFC] Remove arm_sme::populateVectorTransferLoweringPatterns decl (llvm#75442)

Unused since D154867.

Author: c-rhodes

mlir/include/mlir/Dialect/ArmSME/Transforms/Transforms.h

@@ -15,11 +15,6 @@ class LLVMConversionTarget;
 class LLVMTypeConverter;
 class RewritePatternSet;
 
-namespace arm_sme {
-void populateVectorTransferLoweringPatterns(LLVMTypeConverter &converter,
-                                            RewritePatternSet &patterns);
-} // namespace arm_sme
-
 } // namespace mlir
 
 #endif // MLIR_DIALECT_ARMSME_TRANSFORMS_H