FIX: fix the following issues

1. fix the get fc serial number error on M30/M30T
2. fix the identity zenmuse L1 camera failed
3. fix the cpu loading high issue when not used media download apis
4. fix sample cxx compile failed when libusb is not installed

Signed-off-by: DJI-Martin <DJI-Martin@dji.com>

psdk_lib/include/dji_flight_controller.h

@@ -254,7 +254,7 @@ typedef struct {
 } T_DjiFlightControllerHomeLocation; // pack(1)
 
 typedef struct {
-    char serialNum[16];
+    char serialNum[32];
 } T_DjiFlightControllerGeneralInfo;
 #pragma pack()