Resolve string literal error

Space needed between 2 string literals
    [Error] fopen.cpp@204,97: [Pe2486]: user-defined literal operator not found

Author: Deepika

components/storage/blockdevice/COMPONENT_FLASHIAP/TESTS/filesystem/fopen/fopen.cpp

@@ -75,7 +75,7 @@ LittleFileSystem fs("sd");
 
 static char fslittle_fopen_utest_msg_g[FSLITTLE_UTEST_MSG_BUF_SIZE];
 #define FSLITTLE_FOPEN_TEST_MOUNT_PT_NAME      "sd"
-#define FSLITTLE_FOPEN_TEST_MOUNT_PT_PATH      "/"FSLITTLE_FOPEN_TEST_MOUNT_PT_NAME
+#define FSLITTLE_FOPEN_TEST_MOUNT_PT_PATH      "/" FSLITTLE_FOPEN_TEST_MOUNT_PT_NAME
 #define FSLITTLE_FOPEN_TEST_WORK_BUF_SIZE_1    64
 #define FSLITTLE_FOPEN_TEST_FILEPATH_MAX_DEPTH 20
 static const int MAX_TEST_SIZE = 256 * 1024 * 2;