platform/x86: ISST: Fix return value on last invalid resource

When only the last resource is invalid, tpmi_sst_dev_add() is returing
error even if there are other valid resources before. This function
should return error when there are no valid resources.

Here tpmi_sst_dev_add() is returning "ret" variable. But this "ret"
variable contains the failure status of last call to sst_main(), which
failed for the invalid resource. But there may be other valid resources
before the last entry.

To address this, do not update "ret" variable for sst_main() return
status.

If there are no valid resources, it is already checked for by !inst
below the loop and -ENODEV is returned.

Fixes: 9d1d362 ("platform/x86: ISST: Support partitioned systems")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: stable@vger.kernel.org # 6.10+
Link: https://lore.kernel.org/r/20240816163626.415762-1-srinivas.pandruvada@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c

@@ -1549,8 +1549,7 @@ int tpmi_sst_dev_add(struct auxiliary_device *auxdev)
 			goto unlock_free;
 		}
 
-		ret = sst_main(auxdev, &pd_info[i]);
-		if (ret) {
+		if (sst_main(auxdev, &pd_info[i])) {
 			/*
 			 * This entry is not valid, hardware can partially
 			 * populate dies. In this case MMIO will have 0xFFs.