bpf: Fix bpf_dynptr documentation comments

The function argument names were changed but the doc comment was not.
Fix htmldocs build warning by updating doc comments.

Fixes: cce4c40b ("bpf: treewide: Align kfunc signatures to prog point-of-view")
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/d0b0eb05f91e12e5795966153b11998d3fc1d433.1718295425.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/helpers.c

@@ -2433,7 +2433,7 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
 
 /**
  * bpf_dynptr_slice() - Obtain a read-only pointer to the dynptr data.
- * @ptr: The dynptr whose data slice to retrieve
+ * @p: The dynptr whose data slice to retrieve
  * @offset: Offset into the dynptr
  * @buffer__opt: User-provided buffer to copy contents into.  May be NULL
  * @buffer__szk: Size (in bytes) of the buffer if present. This is the
@@ -2504,7 +2504,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr *p, u32 offset,
 
 /**
  * bpf_dynptr_slice_rdwr() - Obtain a writable pointer to the dynptr data.
- * @ptr: The dynptr whose data slice to retrieve
+ * @p: The dynptr whose data slice to retrieve
  * @offset: Offset into the dynptr
  * @buffer__opt: User-provided buffer to copy contents into. May be NULL
  * @buffer__szk: Size (in bytes) of the buffer if present. This is the