[RISCV] Fix -Wexplicit-specialization-storage-class warnings

Author: MaskRay

llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp

@@ -702,10 +702,10 @@ static constexpr DecoderListEntry DecoderList32[]{
 };
 
 // Define bitwidths for various types used to instantiate the decoder.
-template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint16_t> = 16;
-template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
+template <> constexpr uint32_t llvm::MCD::InsnBitWidth<uint16_t> = 16;
+template <> constexpr uint32_t llvm::MCD::InsnBitWidth<uint32_t> = 32;
 // Use uint64_t to represent 48 bit instructions.
-template <> static constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 48;
+template <> constexpr uint32_t llvm::MCD::InsnBitWidth<uint64_t> = 48;
 
 DecodeStatus RISCVDisassembler::getInstruction32(MCInst &MI, uint64_t &Size,
                                                  ArrayRef<uint8_t> Bytes,