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 <[e-mail]>
CC: Boris Ostrovsky <[e-mail]>
CC: Stefano Stabellini <[e-mail]>
Reviewed-by: Konrad Rzeszutek Wilk <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/xen/xen-acpi-cpuhotplug.c

···
 	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 */