drm/amd/display: Tweak the kernel doc for crc_rd_wrk

[Why]
Commit 1c85f3db
("drm/amd/display: Add kernel doc to crc_rd_wrk
field") adds kernel doc for crc_rd_wrk field in
amdgpu_dm.h but it's incorrectly formatted.
Make htmldocs warns:

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h:398: warning:
Incorrect use of kernel-doc format:          * @crc_rd_wrk

[How]
Tweak the kernel doc for crc_rd_wrk.

Fixes: 1c85f3db ("drm/amd/display: Add kernel doc to crc_rd_wrk field")
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -396,7 +396,7 @@ struct amdgpu_display_manager {
 
 #if defined(CONFIG_DRM_AMD_SECURE_DISPLAY)
 	/**
-	 * @crc_rd_wrk
+	 * @crc_rd_wrk:
 	 *
 	 * Work to be executed in a separate thread to communicate with PSP.
 	 */