hwrng: core - Use struct completion for cleanup_done

There is no point in doing a manual completion for cleanup_done
when struct completion fits in perfectly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/linux/hw_random.h

@@ -12,6 +12,7 @@
 #ifndef LINUX_HWRANDOM_H_
 #define LINUX_HWRANDOM_H_
 
+#include <linux/completion.h>
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/kref.h>
@@ -46,7 +47,7 @@ struct hwrng {
 	/* internal. */
 	struct list_head list;
 	struct kref ref;
-	bool cleanup_done;
+	struct completion cleanup_done;
 };
 
 /** Register a new Hardware Random Number Generator driver. */