mfd: Check ACPI device companion before checking resources

Current code in mfd-core calls into ACPI to check resources even
on a system that booted with a DT (on kernels with both DT and ACPI
support compiled in). This triggers ACPI exceptions since we may
end up calling the ACPI interpreter when it has not been initialized:

"ACPI Exception: AE_BAD_PARAMETER, Thread 2064154624 could not acquire
Mutex [0x1] (20150410/utmutex-285)"

This patch fixes the issues by adding a check for an ACPI companion
device before carrying out ACPI resources checks to avoid calling
the ACPI interpreter if the fwnode representing the device is an OF one.

Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/mfd-core.c

@@ -207,9 +207,11 @@ static int mfd_add_device(struct device *parent, int id,
 		}
 
 		if (!cell->ignore_resource_conflicts) {
-			ret = acpi_check_resource_conflict(&res[r]);
-			if (ret)
-				goto fail_alias;
+			if (has_acpi_companion(&pdev->dev)) {
+				ret = acpi_check_resource_conflict(&res[r]);
+				if (ret)
+					goto fail_alias;
+			}
 		}
 	}