RISC-V: PR27158, fixed UJ/SB types and added CSS/CL/CS types for .insn.
* Renamed obsolete UJ/SB types and RVC types, also added CSS/CL(CS) types,
[VALID/EXTRACT/ENCODE macros]
BTYPE_IMM: Renamed from SBTYPE_IMM.
JTYPE_IMM: Renamed from UJTYPE_IMM.
CITYPE_IMM: Renamed from RVC_IMM.
CITYPE_LUI_IMM: Renamed from RVC_LUI_IMM.
CITYPE_ADDI16SP_IMM: Renamed from RVC_ADDI16SP_IMM.
CITYPE_LWSP_IMM: Renamed from RVC_LWSP_IMM.
CITYPE_LDSP_IMM: Renamed from RVC_LDSP_IMM.
CIWTYPE_IMM: Renamed from RVC_UIMM8.
CIWTYPE_ADDI4SPN_IMM: Renamed from RVC_ADDI4SPN_IMM.
CSSTYPE_IMM: Added for .insn without special encoding.
CSSTYPE_SWSP_IMM: Renamed from RVC_SWSP_IMM.
CSSTYPE_SDSP_IMM: Renamed from RVC_SDSP_IMM.
CLTYPE_IMM: Added for .insn without special encoding.
CLTYPE_LW_IMM: Renamed from RVC_LW_IMM.
CLTYPE_LD_IMM: Renamed from RVC_LD_IMM.
RVC_SIMM3: Unused and removed.
CBTYPE_IMM: Renamed from RVC_B_IMM.
CJTYPE_IMM: Renamed from RVC_J_IMM.
* Added new operands and removed the unused ones,
C5: Unsigned CL(CS) immediate, added for .insn directive.
C6: Unsigned CSS immediate, added for .insn directive.
Ci: Unused and removed.
C<: Unused and removed.