samples: usb: mass: fix to support FatFS on external file system

The flash interface header needs to be available regardless of
selected filesystem implementation.

Signed-off-by: Peter Bigot <[email protected]>

Author: pabigot

samples/subsys/usb/mass/src/main.c

@@ -15,6 +15,7 @@
 LOG_MODULE_REGISTER(main);
 
 #if CONFIG_DISK_ACCESS_FLASH
+#include <storage/flash_map.h>
 #if CONFIG_FAT_FILESYSTEM_ELM
 #include <fs/fs.h>
 #include <ff.h>
@@ -30,7 +31,6 @@ static struct fs_mount_t fs_mnt = {
 #elif CONFIG_FILE_SYSTEM_LITTLEFS
 #include <fs/fs.h>
 #include <fs/littlefs.h>
-#include <storage/flash_map.h>
 
 FS_LITTLEFS_DECLARE_DEFAULT_CONFIG(storage);
 static struct fs_mount_t fs_mnt = {