RISC-V: Delete duplicate '#define RISCV_DWARF_VLENB'

gcc/ChangeLog:

	* config/riscv/riscv.h (RISCV_DWARF_VLENB): Delete.

gcc/config/riscv/riscv.h

@@ -1234,8 +1234,6 @@ extern void riscv_remove_unneeded_save_restore_calls (void);
 
 #define REGMODE_NATURAL_SIZE(MODE) riscv_regmode_natural_size (MODE)
 
-#define RISCV_DWARF_VLENB (4096 + 0xc22)
-
 #define DWARF_FRAME_REGISTERS (FIRST_PSEUDO_REGISTER + 1 /* VLENB */)
 
 #define DWARF_REG_TO_UNWIND_COLUMN(REGNO) \