bpf, docs: BPF_FROM_BE exists as alias for BPF_TO_BE

According to include/uapi/linux/bpf.h:

  #define BPF_FROM_LE	BPF_TO_LE
  #define BPF_FROM_BE	BPF_TO_BE

BPF_FROM_BE exists as alias for BPF_TO_BE instead of BPF_TO_LE.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1651139754-4838-3-git-send-email-yangtiezhu@loongson.cn

Documentation/bpf/instruction-set.rst

@@ -157,7 +157,7 @@ Examples:
   dst_reg = htobe64(dst_reg)
 
 ``BPF_FROM_LE`` and ``BPF_FROM_BE`` exist as aliases for ``BPF_TO_LE`` and
-``BPF_TO_LE`` respetively.
+``BPF_TO_BE`` respetively.
 
 
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