fix(risc-v/virt64, cpp): add spaces to fix `Wliteral-suffix`

libcpu/risc-v/virt64/opcode.h

@@ -29,7 +29,7 @@
  * 31      25    20    15      12   7        0
  */
 #define __OPC_INSN_FORMAT_R(opcode, func3, func7, rd, rs1, rs2) \
-    ".insn r "RT_STRINGIFY(opcode)","RT_STRINGIFY(func3)","RT_STRINGIFY(func7)","RT_STRINGIFY(rd)","RT_STRINGIFY(rs1)","RT_STRINGIFY(rs2)
+    ".insn r " RT_STRINGIFY(opcode) "," RT_STRINGIFY(func3) "," RT_STRINGIFY(func7) "," RT_STRINGIFY(rd) "," RT_STRINGIFY(rs1) "," RT_STRINGIFY(rs2)
 
 #ifdef _TOOLCHAIN_SUPP_ZIFENCEI_ISA_
 #define OPC_FENCE_I             "fence.i"
@@ -37,4 +37,4 @@
 #define OPC_FENCE_I             ".long 0x0000100F"
 #endif /* _TOOLCHAIN_SUPP_ZIFENCEI_ISA_ */
 
-#endif /* __OPCODE_H__ */
+#endif /* __OPCODE_H__ */