RISC-V: Indent and GNU coding standards tidy, also aligned the code.

RISC-V: Indent and GNU coding standards tidy, also aligned the code.

bfd/
    * elfnn-riscv.c: Indent, labels and GNU coding standards tidy,
    also aligned the code.
gas/
    * config/tc-riscv.c: Indent and GNU coding standards tidy,
    also aligned the code.
    * config/tc-riscv.h: Likewise.
include/
    * opcode/riscv.h: Indent and GNU coding standards tidy,
    also aligned the code.
opcodes/
    * riscv-opc.c (riscv_gpr_names_abi): Aligned the code.
    (riscv_fpr_names_abi): Likewise.
    (riscv_opcodes): Likewise.
    (riscv_insn_types): Likewise.