RISC-V: Make objdump disassembly work right for binary files.

RISC-V: Make objdump disassembly work right for binary files.

Without the ELF header to set info->endian, it ends up as BFD_UNKNOWN_ENDIAN
which gets printed as big-endian.  But RISC-V instructions are always little
endian, so we can set endian_code correctly, and then set display_endian from
that.  This is similar to how the aarch64 support works, but without the
support for constant pools, as we don't have that on RISC-V.

	opcodes/
	PR binutils/24739
	* riscv-dis.c (riscv_disasemble_insn): Set info->endian_code.
	Set info->display_endian to info->endian_code.