crypto: Change the qcrypto_random_bytes buffer type to void*

Using uint8_t* merely requires useless casts for use with
other types to be filled with randomness.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/crypto/random-gcrypt.c b/crypto/random-gcrypt.c
index 9f1c9ee..7aea4ac 100644
--- a/crypto/random-gcrypt.c
+++ b/crypto/random-gcrypt.c
@@ -24,7 +24,7 @@
 
 #include <gcrypt.h>
 
-int qcrypto_random_bytes(uint8_t *buf,
+int qcrypto_random_bytes(void *buf,
                          size_t buflen,
                          Error **errp G_GNUC_UNUSED)
 {