bpf: Fix bpf_seq_read docs for increased buffer size

Commit af65320 ("bpf: Bump iter seq size to support BTF
representation of large data structures") increased the fixed buffer
size from PAGE_SIZE to PAGE_SIZE << 3, but the docs for the function
didn't get updated at the same time. Update them.

Signed-off-by: T.J. Mercier <[email protected]>
Acked-by: Yonghong Song <[email protected]>

Author: tweej

kernel/bpf/bpf_iter.c

@@ -86,7 +86,7 @@ static bool bpf_iter_support_resched(struct seq_file *seq)
 
 /* bpf_seq_read, a customized and simpler version for bpf iterator.
  * The following are differences from seq_read():
- *  . fixed buffer size (PAGE_SIZE)
+ *  . fixed buffer size (PAGE_SIZE << 3)
  *  . assuming NULL ->llseek()
  *  . stop() may call bpf program, handling potential overflow there
  */