drm/amd/display: Don't use kernel-doc comment in dc_register_software_state struct

drm/amd/display: Don't use kernel-doc comment in dc_register_software_state struct

Sphinx reports kernel-doc warning:

WARNING: ./drivers/gpu/drm/amd/display/dc/dc.h:2796 This comment starts with '/**', but isn't a kernel-doc comment. Refer to Documentation/doc-guide/kernel-doc.rst
 * Software state variables used to program register fields across the display pipeline

Don't use kernel-doc comment syntax to fix it.

Fixes: b0ff344fe70c ("drm/amd/display: Add interface to capture expected HW state from SW state")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>