Fixed potential memory leak in s5j_i2s_initialize function.

Fixed potential memory leak in s5j_i2s_initialize function.

Everytime a new s5j_i2s_s object was created when s5j_i2s_initialize function was called. This lead to memory leak when device on same port is initialized by multiple modules. Now , if the device has been initialised , then the dev object from the initialised s5j_i2s_s object is returned.