fs: remove unused fops from struct char_device_struct

struct char_device_struct::fops is no longer used: remove it.

Signed-off-by: Jiri Olsa <olsajiri@gmail.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>