ieee1394/csr1212: fix false positive kmemcheck report

kmemcheck reports a use of uninitialized memory here, but it's not
a real error. The structure in question has just been allocated, and
the whole field is initialized, but it happens in two steps.

We fix the false positive by inserting a kmemcheck annotation.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>