i965: Initialize registers.

i965: Initialize registers.

The test (file == BAD_FILE) works on registers for which the constructor
has not run because BAD_FILE is zero.  The next commit will move
BAD_FILE in the enum so that it's no longer zero.

In the case of this->outputs, the constructor was being run implicitly,
and we were unnecessarily memsetting is to zero.

Reviewed-by: Emil Velikov <emil.velikov@collabora.co.uk>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>