ANDROID: trusty-ipc: clean up ioctl handling

- Make tipc_compat_ioctl() call tipc_ioctl(), to avoid code duplication
  as more ioctls get added.  This follows the way that .compat_ioctl()
  is typically implemented in drivers; e.g. see ext4_compat_ioctl().

- Fix error code for "unrecognized ioctl".

- Remove user-triggable warning and error messages, or downgrade them to
  debug level.  Kernel convention is to be quiet; userspace can handle
  failures the way it wants to.

- Remove check for _IOC_TYPE() which is redundant because only specific
  ioctl numbers are handled.

- Move compat ioctl definition to internal file, as it doesn't belong in
  the UAPI header.

Change-Id: Ic69db9dbeef823f415cc4be05faf0386e638696f
Signed-off-by: Eric Biggers <ebiggers@google.com>