Fix kernel panic while using XRC_TGT QP type in ibcore.

Attempt to modify XRC_TGT QP type from the user space (ibv_xsrq_pingpong
invocation) will trigger the following kernel panic. It is caused by the
fact that such QPs missed uobject initialization.

Linux commit:
f45765872e7aae7b81feb3044aaf9886b21885ef

MFC after: 1 week
Sponsored by: Mellanox Technologies