drm/i915/flipq: Add intel_flipq_dump()

Add a function for dumping the entries of a specific flip queue.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250624170049.27284-9-ville.syrjala@linux.intel.com