Fix volumd's USBMS splash screen on FW 5.7.x

That clears up my previous queries abour the dual checks ;p.

frontend/device/generic/device.lua

@@ -78,24 +78,24 @@ end
 -- ONLY used for Kindle devices
 function Device:intoScreenSaver()
     local UIManager = require("ui/uimanager")
-    if self.screen_saver_mode == false then
+    if self.charging_mode == false and self.screen_saver_mode == false then
         self.screen:saveCurrentBB()
         self.screen_saver_mode = true
+        -- On FW >= 5.7.2, we sigstop awesome, but we need it to show stuff...
+        if os.getenv("AWESOME_STOPPED") == "yes" then
+            os.execute("killall -cont awesome")
+        end
     end
     UIManager:sendEvent(Event:new("FlushSettings"))
-    -- On FW >= 5.7.2, we sigstop awesome, but we need it to show stuff...
-    if os.getenv("AWESOME_STOPPED") == "yes" then
-        os.execute("killall -cont awesome")
-    end
 end
 
 -- ONLY used for Kindle devices
 function Device:outofScreenSaver()
-    -- On FW >= 5.7.2, put awesome to sleep again...
-    if os.getenv("AWESOME_STOPPED") == "yes" then
-        os.execute("killall -stop awesome")
-    end
-    if self.screen_saver_mode == true then
+    if self.screen_saver_mode == true and self.charging_mode == false then
+        -- On FW >= 5.7.2, put awesome to sleep again...
+        if os.getenv("AWESOME_STOPPED") == "yes" then
+            os.execute("killall -stop awesome")
+        end
         -- wait for native system update screen before we recover saved
         -- Blitbuffer.
         util.usleep(1500000)
@@ -151,12 +151,22 @@ function Device:resume() end
 function Device:usbPlugIn()
     if self.charging_mode == false and self.screen_saver_mode == false then
         self.screen:saveCurrentBB()
+        -- On FW >= 5.7.2, we sigstop awesome, but we need it to show stuff...
+        if os.getenv("AWESOME_STOPPED") == "yes" then
+            os.execute("killall -cont awesome")
+        end
     end
     self.charging_mode = true
 end
 
 function Device:usbPlugOut()
     if self.charging_mode == true and self.screen_saver_mode == false then
+        -- On FW >= 5.7.2, put awesome to sleep again...
+        if os.getenv("AWESOME_STOPPED") == "yes" then
+            os.execute("killall -stop awesome")
+        end
+        -- Same as when going out of screensaver, wait for the native system
+        util.usleep(1500000)
         self.screen:restoreFromSavedBB()
         self.screen:refreshFull()
     end