Revert "drm/i915: re-order if/else ladder for hpd_irq_setup"

Revert "drm/i915: re-order if/else ladder for hpd_irq_setup"

We now use ilk_hpd_irq_setup for all GMCH platforms that do not have
hotplug. These are early gen3 and gen2 devices that now explode on boot
as they try to access non-existent registers.

Fixes: 794d61a19090 ("drm/i915: re-order if/else ladder for hpd_irq_setup")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127145748.29491-1-chris@chris-wilson.co.uk