Gratuitous NULL initializers rarely help and often prevent compiler
from warning about using uninitialized variable. Let's remove them.

Reviewed-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/20191125211407.GA97812@dtor-ws


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>