Power subsystem improvements and bug fixes (#353)

* BT: render icon statically.
* Move API HAL Power init call to api_hal_init.
* API HAL Power: replace stop2 mode with stop1 to ensure usb and lptim2 proper work.

firmware/targets/f4/api-hal/api-hal-power.c

@@ -64,7 +64,7 @@ void api_hal_power_deep_sleep() {
     LL_HSEM_ReleaseLock(HSEM, CFG_HW_RCC_SEMID, 0);
 
     // Prepare deep sleep
-    LL_PWR_SetPowerMode(LL_PWR_MODE_STOP2);
+    LL_PWR_SetPowerMode(LL_PWR_MODE_STOP1);
     LL_LPM_EnableDeepSleep();
 
 #if defined ( __CC_ARM)

firmware/targets/f4/api-hal/api-hal.c

@@ -5,5 +5,6 @@ void api_hal_init() {
     api_hal_vcp_init();
     api_hal_spi_init();
     api_hal_i2c_init();
+    api_hal_power_init();
     api_hal_light_init();
 }