feat: plat: trap: add trait for setting up pc

kernel/src/arch/riscv/trap.rs

@@ -121,6 +121,10 @@ impl TrapContextOps for TrapContext {
         assert!(index < 8, "TrapContext set_reg index out of range");
         self.gprs[index + 9] = value;
     }
+
+    fn set_pc(&mut self, value: usize) {
+        self.sepc = value;
+    }
 }
 
 #[derive(Debug, Default)]

kernel/src/plat/trap.rs

@@ -16,4 +16,5 @@ pub trait TrapContextOps {
 
     fn get_reg(&self, index: usize) -> usize;
     fn set_reg(&mut self, index: usize, value: usize);
+    fn set_pc(&mut self, value: usize);
 }