[ot] hw/opentitan: ot_aes: fix invalid register reference to read current IV value

Signed-off-by: Emmanuel Blot <eblot@rivosinc.com>
(cherry picked from commit 9185a7a)

Author: rivos-eblot

hw/opentitan/ot_aes.c

@@ -1009,7 +1009,7 @@ static uint64_t ot_aes_read(void *opaque, hwaddr addr, unsigned size)
     case R_IV_1:
     case R_IV_2:
     case R_IV_3:
-        val32 = r->keyshare[reg - R_IV_0];
+        val32 = r->iv[reg - R_IV_0];
         break;
     case R_DATA_OUT_0:
     case R_DATA_OUT_1: