[AMDGPU][NFC] Remove a duplicate isInlinableLiteralBF16() declaration.

Author: kosarev

llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h

@@ -1696,9 +1696,6 @@ bool isInlinableLiteralBF16(int16_t Literal, bool HasInv2Pi);
 LLVM_READNONE
 bool isInlinableLiteralFP16(int16_t Literal, bool HasInv2Pi);
 
-LLVM_READNONE
-bool isInlinableLiteralBF16(int16_t Literal, bool HasInv2Pi);
-
 LLVM_READNONE
 bool isInlinableLiteralI16(int32_t Literal, bool HasInv2Pi);