littlefs2: Properly init class variables (#451)

* littlefs2: Properly init class variables

* Style fix

Author: multiplemonomials

storage/filesystem/littlefsv2/include/littlefsv2/LittleFileSystem2.h

@@ -289,9 +289,9 @@ class LittleFileSystem2 : public mbed::FileSystem {
 #endif //!(DOXYGEN_ONLY)
 
 private:
-    lfs2_t _lfs; // The actual file system
-    struct lfs2_config _config;
-    mbed::BlockDevice *_bd; // The block device
+    lfs2_t _lfs{}; // The actual file system
+    struct lfs2_config _config {};
+    mbed::BlockDevice *_bd = nullptr; // The block device
 
     // thread-safe locking
     rtos::Mutex _mutex;

storage/filesystem/littlefsv2/source/LittleFileSystem2.cpp

@@ -149,7 +149,6 @@ LittleFileSystem2::LittleFileSystem2(const char *name, BlockDevice *bd,
                                      lfs2_size_t cache_size, lfs2_size_t lookahead_size)
     : FileSystem(name)
 {
-    memset(&_config, 0, sizeof(_config));
     _config.block_size = block_size;
     _config.block_cycles = block_cycles;
     _config.cache_size = cache_size;