ANDROID: dm: update ->prepare_ioctl callback

Add the new 'bool *forward' parameter to .prepare_ioctl which was
introduced in commit 4862c886 ("dm: Allow .prepare_ioctl to handle
ioctls directly"), along with the cmd and arg to handle the callback
correctly if needed.

Fixes: 4862c886 ("dm: Allow .prepare_ioctl to handle ioctls directly")
Change-Id: I00abc420009b18a8726fa5e888db84a102b89e9b
Signed-off-by: Carlos Llamas <cmllamas@google.com>