PR InfiniTimeOrg#648: Improve sleep time

Squashed commit of the following:

commit d213ae7
Author: Riku Isokoski <riksu9000@gmail.com>
Date:   Mon Sep 20 11:38:33 2021 +0300

    Fix DisplayAppRecovery

commit de7cc1f
Merge: a825fcb 5855906
Author: Riku Isokoski <riksu9000@gmail.com>
Date:   Sat Sep 18 19:19:03 2021 +0300

    Merge branch 'develop' into del_dispapp_lcd

commit a825fcb
Author: Riku Isokoski <riksu9000@gmail.com>
Date:   Mon Sep 6 11:59:54 2021 +0300

    Remove lcd from DisplayApp

src/displayapp/DisplayApp.cpp

@@ -186,12 +186,10 @@ void DisplayApp::Refresh() {
           brightnessController.Lower();
           vTaskDelay(100);
         }
-        lcd.DisplayOff();
         PushMessageToSystemTask(Pinetime::System::Messages::OnDisplayTaskSleeping);
         state = States::Idle;
         break;
       case Messages::GoToRunning:
-        lcd.DisplayOn();
         brightnessController.Restore();
         state = States::Running;
         break;

src/drivers/St7789.h

@@ -22,9 +22,6 @@ namespace Pinetime {
 
       void DrawBuffer(uint16_t x, uint16_t y, uint16_t width, uint16_t height, const uint8_t* data, size_t size);
 
-      void DisplayOn();
-      void DisplayOff();
-
       void Sleep();
       void Wakeup();
 
@@ -42,6 +39,9 @@ namespace Pinetime {
       void DisplayInversionOn();
       void NormalModeOn();
       void WriteToRam();
+      void DisplayOn();
+      void DisplayOff();
+
       void SetAddrWindow(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1);
       void WriteCommand(uint8_t cmd);
       void WriteSpi(const uint8_t* data, size_t size);