riscv: kprobes: simulate c.beqz and c.bnez

kprobes currently rejects instruction c.beqz and c.bnez. Implement them.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/1d879dba4e4ee9a82e27625d6483b5c9cfed684f.1690704360.git.namcaov@gmail.com


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