bpf, arm32: fix inconsistent naming about emit_a32_lsr_{r64,i64}

The names for BPF_ALU64 | BPF_ARSH are emit_a32_arsh_*,
the names for BPF_ALU64 | BPF_LSH are emit_a32_lsh_*, but
the names for BPF_ALU64 | BPF_RSH are emit_a32_lsr_*.

For consistence reason, let's rename emit_a32_lsr_* to
emit_a32_rsh_*.

This patch also corrects a wrong comment.

Fixes: 39c13c20

 ("arm: eBPF JIT compiler")
Signed-off-by: Wang YanQing <udknight@gmail.com>
Cc: Shubham Bansal <illusionist.neo@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux@armlinux.org.uk
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>