drm/mst: switch to guid_gen() to generate valid GUIDs

drm/mst: switch to guid_gen() to generate valid GUIDs

Instead of just smashing jiffies into a GUID, use guid_gen() to generate
RFC 4122 compliant GUIDs.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240812122312.1567046-2-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>