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>

crypto/random-gnutls.c

@@ -26,7 +26,7 @@
 #include <gnutls/gnutls.h>
 #include <gnutls/crypto.h>
 
-int qcrypto_random_bytes(uint8_t *buf,
+int qcrypto_random_bytes(void *buf,
                          size_t buflen,
                          Error **errp)
 {