Changed IMST boards default power source to USB_POWER

Author: mluis1

src/boards/SKiM880B/board.c

@@ -471,7 +471,7 @@ void SysTick_Handler( void )
 
 uint8_t GetBoardPowerSource( void )
 {
-    return BATTERY_POWER;
+    return USB_POWER;
 }
 
 /**

src/boards/SKiM881AXL/board.c

@@ -444,7 +444,7 @@ void SysTick_Handler( void )
 
 uint8_t GetBoardPowerSource( void )
 {
-    return BATTERY_POWER;
+    return USB_POWER;
 }
 
 /**

src/boards/SKiM980A/board.c

@@ -471,7 +471,7 @@ void SysTick_Handler( void )
 
 uint8_t GetBoardPowerSource( void )
 {
-    return BATTERY_POWER;
+    return USB_POWER;
 }
 
 /**