net-timestamp: correct the use of SOF_TIMESTAMPING_RAW_HARDWARE

SOF_TIMESTAMPING_RAW_HARDWARE is a report flag which passes the
timestamps generated by either SOF_TIMESTAMPING_TX_HARDWARE or
SOF_TIMESTAMPING_RX_HARDWARE to the userspace all the time.

So let us revise the doc here.

Link: https://lore.kernel.org/all/66d8c21d3042a_163d93294cb@willemb.c.googlers.com.notmuch/Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Link: https://patch.msgid.link/20240908124141.39628-1-kerneljasonxing@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/timestamping.rst

@@ -158,7 +158,8 @@ SOF_TIMESTAMPING_SYS_HARDWARE:
 
 SOF_TIMESTAMPING_RAW_HARDWARE:
   Report hardware timestamps as generated by
-  SOF_TIMESTAMPING_TX_HARDWARE when available.
+  SOF_TIMESTAMPING_TX_HARDWARE or SOF_TIMESTAMPING_RX_HARDWARE
+  when available.
 
 
 1.3.3 Timestamp Options