fix samd51p20a

Author: hathach

CMSIS-Atmel/CMSIS/Device/ATMEL/samd51/include/samd51p20a.h

@@ -544,8 +544,8 @@ void SDHC1_Handler               ( void );
  * \brief Configuration of the Cortex-M4 Processor and Core Peripherals
  */
 
-//#ifndef LITTLE_ENDIAN
-#define LITTLE_ENDIAN          1        
+#ifndef LITTLE_ENDIAN
+#define LITTLE_ENDIAN          1        
 #endif
 #define __CM4_REV              1         /*!< Core revision r0p1 */
 #define __DEBUG_LVL            3         /*!< Full debug plus DWT data matching */