Fix triggers for accesses wider than XLEN

I believe that @en-sc's comment here is correct:
https://github.com/riscv-software-src/riscv-isa-sim/pull/2161#discussion_r2564958203

Nevertheless, failing an assertion when someone sets a trigger on memory
accessed by a wide access is not reasonable behavior for Spike.  Better to
do something that follows the principle of least surprise, despite the
debug spec's lack of clarity on this point.

riscv/mmu.cc

@@ -223,9 +223,8 @@ void mmu_t::check_triggers(triggers::operation_t operation,
   reg_t addr, bool virt, std::size_t data_size, const std::uint8_t* bytes)
 {
   assert(data_size > 0);
-  assert(data_size <= sizeof(reg_t));
-  check_triggers(operation, addr, virt,
-    data_size, reg_from_bytes(data_size, bytes));
+
+  check_triggers(operation, addr, virt, data_size, reg_from_bytes(std::min(data_size, sizeof(reg_t)), bytes));
 }
 
 void mmu_t::check_triggers(triggers::operation_t operation,