[RISCV] Reduce dynamic relocations for RISCVOpcodesList table. NFC

Inline the strings directly into the table instead of storing a pointer.
Similar to what was done for other searchable tables in the last couple
months.

Author: topperc

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h

@@ -484,8 +484,8 @@ struct SysReg {
 
 namespace RISCVInsnOpcode {
 struct RISCVOpcode {
-  const char *Name;
-  unsigned Value;
+  char Name[10];
+  uint8_t Value;
 };
 
 #define GET_RISCVOpcodesList_DECL