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

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[email protected]/

Cc: Matt Roper <[email protected]>
Reviewed-by: Ville Syrjälä <[email protected]>
Signed-off-by: Gustavo Sousa <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]