drm/i915/display: Zero-initialize frame/scanline counts in tracepoints

In an upcoming change, we will also add support for logging
frame/scanline counts for pipe D in relevant tracepoints.

In [1], Matt mentioned the possibility of having garbage in those counts
for pipe D on a platform containing only 3 pipes. Indeed, it has been
verified that the counts for the extra pipe would not be
zero-initialized by the tracing system.

Since it is also possible that the same would happen for a fused-off
pipe, let's go ahead and add the logic to zero-initialize the arrays
now.

[1] https://lore.kernel.org/all/20240918224927.GU5091@mdroper-desk1.amr.corp.intel.com/



Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241016135300.21428-3-gustavo.sousa@intel.com