RISC-V: add ebreak instructions to definitions

kprobes need to match ebreak instructions, so add the necessary
data to enable us to centralize that functionality.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20221223221332.4127602-5-heiko@sntech.de


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>