drivers: wifi: siwx917: Split out NET_OFFLOAD code

siwx917_wifi.c is currently pretty large while a big part is in fact
only used to manage socket API. Split out the socket management and only
keep 802.11 management in siwx917_wifi.c.

This commit do not introduce any change in the code. The code is only
relocated.

Signed-off-by: Jérôme Pouiller <[email protected]>

Author: jerome-pouiller

drivers/wifi/siwx917/CMakeLists.txt

@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: Apache-2.0
 # Copyright (c) 2024 Silicon Laboratories Inc.
 
-zephyr_library_sources_ifdef(CONFIG_WIFI_SIWX917 siwx917_wifi.c)
+zephyr_library_sources_ifdef(CONFIG_WIFI_SIWX917 siwx917_wifi.c siwx917_wifi_socket.c)