[BinaryFormat][RISCV] Delete R_RISCV_CHERI_SIZE

This has never actually been used (it only appeared to be used in LLD,
but never was in practice), nor is it supported by any run-time linker.

Author: jrtc27

llvm/include/llvm/BinaryFormat/ELFRelocs/RISCV.def

@@ -59,7 +59,7 @@ ELF_RELOC(R_RISCV_PLT32,             59)
 ELF_RELOC(R_RISCV_CHERI_CAPTAB_PCREL_HI20,        192)
 ELF_RELOC(R_RISCV_CHERI_CAPABILITY,               193)
 // 194 reserved
-ELF_RELOC(R_RISCV_CHERI_SIZE,                     195)
+// 195 reserved
 ELF_RELOC(R_RISCV_CHERI_TPREL_CINCOFFSET,         196) // Deprecated
 ELF_RELOC(R_RISCV_CHERI_TLS_IE_CAPTAB_PCREL_HI20, 197) // Deprecated
 ELF_RELOC(R_RISCV_CHERI_TLS_GD_CAPTAB_PCREL_HI20, 198) // Deprecated