drm/i915: Indicate which pipe lied about its interrupts

Indicate which pipe signalled the spurious DE PIPE interrupt.
Might help with debugging a bit if we know where the interrupt
is supposedly coming from.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250513092820.18715-1-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>