Xen / ACPI / processor: Remove unneeded NULL check

Before xen_acpi_processor_enable() is called, struct acpi_processor *pr is
allocated in xen_acpi_processor_add() and checked if it's NULL, so no need
to check again when passed to xen_acpi_processor_enable(), just remove it.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/xen/xen-acpi-cpuhotplug.c

@@ -46,13 +46,7 @@ static int xen_acpi_processor_enable(struct acpi_device *device)
 	unsigned long long value;
 	union acpi_object object = { 0 };
 	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
-	struct acpi_processor *pr;
-
-	pr = acpi_driver_data(device);
-	if (!pr) {
-		pr_err(PREFIX "Cannot find driver data\n");
-		return -EINVAL;
-	}
+	struct acpi_processor *pr = acpi_driver_data(device);
 
 	if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
 		/* Declared with "Processor" statement; match ProcessorID */