s390/trng: set quality to 1024

The s390-trng does provide 100% entropy. The quality value is supported
to be between 1 and 1024 and not 1..1000.  Use 1024 to make this driver
the preferred one. If we ever have a better driver that has the same
quality but is faster we can change this again when merging the new
driver. No need to be conservative.

This makes sure that the hw variant is preferred over things like
virtio-rng, where the hypervisor has a potential to be misconfigured
and thus should have a slightly lower confidence.

Cc: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

drivers/char/hw_random/s390-trng.c

@@ -192,14 +192,15 @@ static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 
 /*
  * hwrng register struct
- * The trng is suppost to have 100% entropy, and thus
- * we register with a very high quality value.
+ * The trng is supposed to have 100% entropy, and thus we register with a very
+ * high quality value. If we ever have a better driver in the future, we should
+ * change this value again when we merge this driver.
  */
 static struct hwrng trng_hwrng_dev = {
 	.name		= "s390-trng",
 	.data_read	= trng_hwrng_data_read,
 	.read		= trng_hwrng_read,
-	.quality	= 999,
+	.quality	= 1024,
 };