drm/i915: Allocate the pipe_crc->entires with kcalloc()

pipe_crc->entries[] is an array so allocate with kcalloc() instead of
kzalloc().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>