atlflight/eagle: minor fixes to get it running again

- fixed df_ltc2946_wrapper battery dependency
 - fixed px4::atomic fetch_add for QuRT
 - updated PX4 QuRT SPI wrapper to set bus frequency
 - renamed "qurt-default" configs to just "qurt"

platforms/common/include/px4_platform_common/atomic.h

@@ -105,7 +105,12 @@ public:
 	 */
 	inline T fetch_add(T num)
 	{
+#ifdef __PX4_QURT
+		// TODO: fix
+		return _value++;
+#else
 		return __atomic_fetch_add(&_value, num, __ATOMIC_SEQ_CST);
+#endif
 	}
 
 	/**