drm/radeon/ci add comment to document intentionally unreachable code

commit d967be9b80a5 ("drm/radeon/ci: disable needless sclk changes")
introduces an unreachable if(C != C) conditional code section
flagged by coccinelle script bad_conditional.cocci:

Add a comment to make it clear that this is intentional.

Fixes: d967be9b80a5 ("drm/radeon/ci: disable needless sclk changes")

Signed-off-by: Nicholas Mc Guire <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/ci_dpm.c

···
 	if (i >= sclk_table->count) {
 		pi->need_update_smu7_dpm_table |= DPMTABLE_OD_UPDATE_SCLK;
 	} else {
-		/* XXX check display min clock requirements */
+		/* XXX The current code always reprogrammed the sclk levels,
+		 * but we don't currently handle disp sclk requirements
+		 * so just skip it.
+		 */
 		if (CISLAND_MINIMUM_ENGINE_CLOCK != CISLAND_MINIMUM_ENGINE_CLOCK)
 			pi->need_update_smu7_dpm_table |= DPMTABLE_UPDATE_SCLK;
 	}