Report the faulting virtual address in tval

In some cases we were reporting the translated value instead, but the
privileged spec text requires the virtual address:
```
If mtval is written with a nonzero value when a breakpoint,
address-misaligned, access-fault, or page-fault exception occurs on an
instruction fetch, load, or store, then mtval will contain the faulting
virtual address.
```

model/riscv_insts_aext.sail

@@ -220,7 +220,7 @@ function clause execute (STORECON(aq, rl, rs2, rs1, width, rd)) = {
  _ => internal_error(__FILE__, __LINE__, "STORECON expected word or double")
  };
  match (eares) {
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL },
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
  MemValue(_) => {
  rs2_val = X(rs2);
  let res : MemoryOpResult(bool) = match (width, sizeof(xlen)) {
@@ -233,7 +233,7 @@ function clause execute (STORECON(aq, rl, rs2, rs1, width, rd)) = {
  match (res) {
  MemValue(true) => { X(rd) = zero_extend(0b0); cancel_reservation(); RETIRE_SUCCESS },
  MemValue(false) => { X(rd) = zero_extend(0b1); cancel_reservation(); RETIRE_SUCCESS },
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL }
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL }
  }
  }
  }
@@ -303,7 +303,7 @@ function clause execute (AMO(op, aq, rl, rs2, rs1, width, rd)) = {
  DOUBLE => X(rs2)
  };
  match (eares) {
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL },
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
  MemValue(_) => {
  let mval : MemoryOpResult(xlenbits) = match (width, sizeof(xlen)) {
  (BYTE, _) => extend_value(is_unsigned, mem_read(ReadWrite(Data, Data), addr, 1, aq, aq & rl, true)),
@@ -313,7 +313,7 @@ function clause execute (AMO(op, aq, rl, rs2, rs1, width, rd)) = {
  _ => internal_error(__FILE__, __LINE__, "Unexpected AMO width")
  };
  match (mval) {
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL },
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
  MemValue(loaded) => {
  let result : xlenbits =
  match op {
@@ -347,7 +347,7 @@ function clause execute (AMO(op, aq, rl, rs2, rs1, width, rd)) = {
  match (wval) {
  MemValue(true) => { X(rd) = rval; RETIRE_SUCCESS },
  MemValue(false) => { internal_error(__FILE__, __LINE__, "AMO got false from mem_write_value") },
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL }
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL }
  }
  }
  }

model/riscv_insts_fext.sail

@@ -458,7 +458,7 @@ function clause execute (STORE_FP(imm, rs2, rs1, width)) = {
  DOUBLE => mem_write_ea(addr, 8, aq, rl, false)
  };
  match (eares) {
- MemException(e) => { handle_mem_exception(addr, e); RETIRE_FAIL },
+ MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
  MemValue(_) => {
  let rs2_val = F(rs2);
  match (width) {