riscv, bpf: Fix typo in comment

We can use either "instruction" or "insn" in the comment.

Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Link: https://lore.kernel.org/r/20240507111618.437121-1-xiao.w.wang@intel.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>