This commit changes the firmware handling from requesting each
firmware file as a ROM module that is checked against a list of
known images (including their size) to requesting each file via
the local VFS of the 'wifi_drv'. This allows for using the original
probing mechanism that tries to select a matching firmware version.
The 'repos/dde_linux/src/drivers/wifi/README' file contains more
detailed information on how to configure the driver.
Issue #4861.
Querying the RFKILL state led to execution of the Lx_kit::scheduler by
the pthread running the wpa_supplicant. As this may not happen the
RFKILL state is now solely managed by the driver and only the cached
state is read by the supplicant.
Fixes#4537.
