target/xtensa: don't specify windowed registers manually

Use libisa to extract whether opcode uses windowed registers and
construct mask based on that. This only leaves special case for the
'entry' opcode, as it needs to probe a register dynamically.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

target/xtensa/helper.c

@@ -88,6 +88,7 @@ static void init_libisa(XtensaConfig *config)
 #endif
         config->opcode_ops[i] = ops;
     }
+    config->a_regfile = xtensa_regfile_lookup(config->isa, "AR");
 }
 
 void xtensa_finalize_config(XtensaConfig *config)