drm/i915: Remove __maybe_unused from mtl_info

The attribute __maybe_unused should remain only until the respective
info is not in the pciidlist. The info can't be added together
with its definition because that would cause the driver to automatically
probe for the device, while it's still not ready for that. However once
pciidlist contains it, the attribute can be removed.

Fixes: 78353039 ("drm/i915/mtl: Add MeteorLake PCI IDs")
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221214194944.3670344-1-lucas.demarchi@intel.com