drm/i915: Make IRQ reset and postinstall multi-gt aware

In multi-gt systems IRQs need to be reset and enabled per GT.

This might add some redundancy when handling interrupts for
engines that might not exist in every tile, but helps to keep the
code cleaner and more understandable.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230417235356.1291060-1-andi.shyti@linux.intel.com