staging: gdm72xx: Modify a struct allocation to match coding standards

Fixes the following checkpatch.pl issue:

CHECK: Prefer kmalloc(sizeof(*entry)...) over kmalloc(sizeof(struct qos_entry_s)...)
Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm72xx/gdm_qos.c

@@ -56,7 +56,7 @@ static void *alloc_qos_entry(void)
 	}
 	spin_unlock_irqrestore(&qos_free_list.lock, flags);
 
-	entry = kmalloc(sizeof(struct qos_entry_s), GFP_ATOMIC);
+	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 	return entry;
 }