Input: ims-pcu - sanity check against missing interfaces

commit a0ad220c96692eda76b2e3fd7279f3dcd1d8a8ff upstream.

A malicious device missing interface can make the driver oops.
Add sanity checking.

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>