xen: pcpu: remove unnecessary __ref annotation

The __ref annotation has been there since many years now, but the
reason why it has been added has been removed from the code long ago.

[jgross: clarify commit message]

Cc: Juergen Gross <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Sergio Miguéns Iglesias <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>

Author: lonyelon

drivers/xen/pcpu.c

@@ -105,7 +105,7 @@ static ssize_t online_show(struct device *dev,
 	return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
 }
 
-static ssize_t __ref online_store(struct device *dev,
+static ssize_t online_store(struct device *dev,
 				  struct device_attribute *attr,
 				  const char *buf, size_t count)
 {