Update system_stm32f4xx.c

In die void SystemInit folgendes hinzugefügt:
/*FPU settings */
	
#if ( __FPU_PRESENT == 1) && ( __FPU_USED == 1)
	SCB -> CPACR |= ((3UL << 10*2) |(3UL << 11*2) ); /* set CP10 and CP11 Full Access */
#endif