[GFS2] Remove unused ioctls and unused structure

/* Ioctls implemented */

#define GFS2_IOCTL_IDENTIFY      _GFS2C_(1)

#define GFS2_IOCTL_SUPER         _GFS2C_(2)

#define GFS2_IOCTL_SETFLAGS      _GFS2C_(3)

#define GFS2_IOCTL_GETFLAGS      _GFS2C_(4)

struct gfs2_ioctl {

	unsigned int gi_argc;

	const char **gi_argv;

        char __user *gi_data;

	unsigned int gi_size;

	uint64_t gi_offset;

};

#endif /* ___GFS2_IOCTL_DOT_H__ */