[ot] hw/opentitan: ot_csrng: fix connection management

1. inverted detection of a previous EDN connection
2. the filler_fn function now tracks whether an EDN is connected or not,
   the instantiation status was a left over from the initial implementation

Signed-off-by: Emmanuel Blot <eblot@rivosinc.com>

Author: rivos-eblot

hw/opentitan/ot_csrng.c

@@ -432,7 +432,7 @@ ot_csnrg_connect_hw_app(OtCSRNGState *s, unsigned app_id, qemu_irq req_sts,
     OtCSRNGInstance *inst = &s->instances[app_id];
 
     if (!filler_fn) {
-        if (inst->hw.filler) {
+        if (!inst->hw.filler) {
             xtrace_ot_csrng_info("HW app was not connected", app_id);
             return NULL;
         }
@@ -1020,7 +1020,7 @@ static void ot_csrng_handle_enable(OtCSRNGState *s)
         /* skip SW instance */
         for (unsigned ix = 0u; ix < OT_CSRNG_HW_APP_MAX; ix++) {
             OtCSRNGInstance *inst = &s->instances[ix];
-            if (ot_csrng_drng_is_instantiated(inst)) {
+            if (inst->hw.filler) {
                 qemu_log_mask(LOG_GUEST_ERROR,
                               "%s: Forcing CSRNG disablement while EDN #%u "
                               "still active\n",