AP_HAL_Linux: default USE_FRAM to 0 for all boards

This disables FRAM usage in PXF and erleboard. The reason is it's
failing and not being used. Right now we get this on startup:

	root@beaglebone:~# ./ArduCopter.elf
	FRAM: Online
	Storage: FRAM is getting reset to default values
	Failed to read FRAM

Testing with valgrind also reveals some invalid memory reads. Let's
disable it for now to be common with other boards.

libraries/AP_HAL_Linux/Storage.h

@@ -1,11 +1,7 @@
 #ifndef __AP_HAL_LINUX_STORAGE_H__
 #define __AP_HAL_LINUX_STORAGE_H__
 
-#if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ERLEBOARD || CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_PXF
-#define LINUX_STORAGE_USE_FRAM 1
-#else
 #define LINUX_STORAGE_USE_FRAM 0
-#endif
 
 #include <AP_HAL/AP_HAL.h>
 #include "AP_HAL_Linux_Namespace.h"