Enable OT OTBN scramble test

Match https://github.com/renode/renode/commit/c32ecdf50

Also cleanup OTBN ECDSA test macro

Change-Id: I161ede8ab4cedb41ec2be4ca130a9d1cc700d75e

opentitan_peripherals_test.robot

diff --git a/opentitan_peripherals_test.robot b/opentitan_peripherals_test.robot
index 5476ec6..eb9f590 100644
--- a/opentitan_peripherals_test.robot
+++ b/opentitan_peripherals_test.robot
@@ -240,17 +240,15 @@
     Run Test               ${SRAM_CTRL_BIN}
 
 Should Pass OTBN ECDSA Test
-    Prepare Test           ${OTBN_ECDSA_BIN}
-    Execute Test
+    Run Test           ${OTBN_ECDSA_BIN}
 
 Should Pass OTBN IRQ Test
     Run Test               ${OTBN_IRQ_BIN}
 
-# Test is marked as broken: https://github.com/lowRISC/opentitan/blob/master/sw/device/tests/BUILD#L1411-L1416
 Should Pass OTBN Memory Scramble Test
-    [Tags]                 skipped
     Prepare Test           ${OTBN_SCRAMBLE_BIN}
-    Execute Command        cpu0 MaximumBlockSize 1
+    Execute Command        cpu0 NMIVectorAddress 0x2000047c
+    Execute Command        cpu0 NMIVectorLength 1
     Execute Test
 
 Should Pass OTBN Randomness Test