drm/i915/display: pre-initialize some values in probe_gmdid_display()

When intel_display_device_probe() (and, subsequently,
probe_gmdid_display()) returns, the caller expects ver, rel and step
to be initialized.  Since there's no way to check that there was a
failure and no_display was returned without some further refactoring,
pre-initiliaze all these values to zero to keep it simple and safe.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230601090338.80284-1-luciano.coelho@intel.com