kernel: T9197: enable CONFIG_IWLMLD

Kernel 6.18 moved Intel BE200/BE-series (Wi-Fi 7) devices to the new
iwlmld op-mode driver: their dev_info entries in iwlwifi's pcie/drv.c
are guarded by IS_ENABLED(CONFIG_IWLMLD). The VyOS kernel config enables
IWLWIFI/IWLDVM/IWLMVM but not IWLMLD, so BE-series support is compiled
out and probing fails with error -22 (no wlan interface is created).

Enable IWLMLD as a module on x86 and arm64, matching the existing
IWLDVM/IWLMVM op-modes. The firmware these devices need is already
shipped by the linux-firmware package.

Author: srnoth

scripts/package-build/linux-kernel/config/arm64/vyos_defconfig

@@ -2215,6 +2215,7 @@ CONFIG_IWLWIFI=m
 CONFIG_IWLWIFI_LEDS=y
 CONFIG_IWLDVM=m
 CONFIG_IWLMVM=m
+CONFIG_IWLMLD=m
 CONFIG_IWLWIFI_OPMODE_MODULAR=y
 
 #

scripts/package-build/linux-kernel/config/x86/vyos_defconfig

@@ -2074,6 +2074,7 @@ CONFIG_IWLWIFI=m
 CONFIG_IWLWIFI_LEDS=y
 CONFIG_IWLDVM=m
 CONFIG_IWLMVM=m
+CONFIG_IWLMLD=m
 CONFIG_IWLWIFI_OPMODE_MODULAR=y
 
 #