Pocketbook: switch the Wi-Fi on before attempting to connect (#8546)

Fixes #4747.

Apparently, inkview.NetConnect() doesn’t enable the Wi-Fi on its own,
this results in a failure if the device has been put into the sleep or
standby mode, when the Wi-Fi hardware is powered down.

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

frontend/device/pocketbook/device.lua

@@ -342,6 +342,7 @@ end
 
 function PocketBook:initNetworkManager(NetworkMgr)
     function NetworkMgr:turnOnWifi(complete_callback)
+        inkview.WiFiPower(1)
         if inkview.NetConnect(nil) ~= C.NET_OK then
             logger.info('NetConnect failed')
         end