Map timer_smc on Nexus to cpu1@5

- Although the timer does have a PLIC interrupt, we never unmask that --
  and instead get the interrupt via the dedicated timer interrupt
  vector, so update the Renode config to reflect that.

Change-Id: I6558f5fcedc0c1cae97cbf5ddd835c1408b3d8fb

platforms/nexus_smc.repl

diff --git a/platforms/nexus_smc.repl b/platforms/nexus_smc.repl
index 16f3843..109a99e 100644
--- a/platforms/nexus_smc.repl
+++ b/platforms/nexus_smc.repl
@@ -24,7 +24,7 @@
 // RV_TIMER_SMC, timer for Cantrip kernel.
 timer_smc: @ sysbus 0x54010000
     frequency: 2500000
-    IRQ -> smc_plic@9
+    IRQ -> cpu1@5
 
 // Timer for Cantrip software timer service.
 timer_smc_sw: @ sysbus 0x54011000