drm/i915/mst: limit DP MST ESI service loop

drm/i915/mst: limit DP MST ESI service loop

The loop in intel_dp_check_mst_status() keeps servicing interrupts
originating from the sink without bound. Add an upper bound to the new
interrupts occurring during interrupt processing to not get stuck on
potentially stuck sink devices. Use arbitrary 32 tries to clear incoming
interrupts in one go.

Discovered using AI-assisted static analysis confirmed by Intel Product
Security.

Note: The condition likely pre-dates the commit in the Fixes: tag, but
this is about as far back as a backport has any chance of
succeeding. Before that, the retry had a goto.

Reported-by: Martin Hodo <martin.hodo@intel.com>
Fixes: 3c0ec2c2d594 ("drm/i915: Flatten intel_dp_check_mst_status() a bit")
Cc: stable@vger.kernel.org # v5.8+
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260625142204.1078287-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit b4ea5272133059acb493cc36599071a9e852ec2e)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>