Update src/ipc/ipc3/readme.md

ipc_cmd_handler() is referenced as the initial routing function, but there is no such symbol in IPC3; the handler entry point is ipc_cmd()

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Liam Girdwood <lgirdwood@gmail.com>

Author: lgirdwood

src/ipc/ipc3/readme.md

@@ -8,7 +8,7 @@ The IPC3 architecture treats streaming, DAI configurations, and pipeline managem
 
 ## Command Structure and Routing
 
-Every message received is placed into an Rx buffer and initially routed to `ipc_cmd_handler()`. Based on the `cmd` inside the `sof_ipc_cmd_hdr`, it delegates to one of the handler subsystems:
+Every message received is placed into an Rx buffer and initially routed to `ipc_cmd()`. Based on the `cmd` inside the `sof_ipc_cmd_hdr`, it delegates to one of the handler subsystems:
 
 * `ipc_glb_stream_message`: Stream/Pipeline configuration and states
 * `ipc_glb_dai_message`: DAI parameters and formats