drm/amd/pm: Return -EOPNOTSUPP for unsupported OD_MCLK on smu_v13_0_6

When SET_UCLK_MAX capability is absent, return -EOPNOTSUPP from
smu_v13_0_6_emit_clk_levels() for OD_MCLK instead of 0. This makes
unsupported OD_MCLK reporting consistent with other clock types
and allows callers to skip the entry cleanly.

Signed-off-by: Asad Kamal <asad.kamal@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d82e0a7)
Cc: stable@vger.kernel.org

Author: Asad Kamal

drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_6_ppt.c

@@ -1391,7 +1391,7 @@ static int smu_v13_0_6_emit_clk_levels(struct smu_context *smu,
 		break;
 	case SMU_OD_MCLK:
 		if (!smu_v13_0_6_cap_supported(smu, SMU_CAP(SET_UCLK_MAX)))
-			return 0;
+			return -EOPNOTSUPP;
 
 		size += sysfs_emit_at(buf, size, "%s:\n", "OD_MCLK");
 		size += sysfs_emit_at(buf, size, "0: %uMhz\n1: %uMhz\n",