drm/i915: Don't pass stack garbage to pcode in the second data register

drm/i915: Don't pass stack garbage to pcode in the second data register

Zero initialize val2 so that we don't pass stack garbage to
the pcode qgv read command. I suspect in this case pcode
just ignores the initial value in that registers, but better
safe than sorry.

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190710134937.25835-1-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>