drm/i915: silence rpm wakeref asserts on GEN11_GU_MISC_IIR access

drm/i915: silence rpm wakeref asserts on GEN11_GU_MISC_IIR access

Commit 8d9908e8fe9c ("drm/i915/display: remove small micro-optimizations
in irq handling") not only removed the optimizations, it also enabled
wakeref asserts for the GEN11_GU_MISC_IIR access. Silence the asserts by
wrapping the access inside intel_display_rpm_assert_{block,unblock}().

Reported-by: "Jason A. Donenfeld" <Jason@zx2c4.com>
Closes: https://lore.kernel.org/r/aG0tWkfmxWtxl_xc@zx2c4.com
Fixes: 8d9908e8fe9c ("drm/i915/display: remove small micro-optimizations in irq handling")
Cc: stable@vger.kernel.org # v6.13+
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20250805115656.832235-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>