hw/misc/aspeed_hace: Do not crash if address_space_map() failed

hw/misc/aspeed_hace: Do not crash if address_space_map() failed

address_space_map() can fail:

  uart:~$ hash test
  sha256_test
  tv[0]:
  Segmentation fault: 11
  Thread 3 "qemu-system-arm" received signal SIGSEGV, Segmentation fault.
  gen_acc_mode_iov (req_len=0x7ffff18b7778, id=<optimized out>, iov=0x7ffff18b7780, s=0x555556ce0bd0)
      at ../hw/misc/aspeed_hace.c:171
  171         if (has_padding(s, &iov[id], *req_len, &total_msg_len, &pad_offset)) {
  (gdb) bt
  #0  gen_acc_mode_iov (req_len=0x7ffff18b7778, id=<optimized out>, iov=0x7ffff18b7780, s=0x555556ce0bd0)
      at ../hw/misc/aspeed_hace.c:171
  #1  do_hash_operation (s=s@entry=0x555556ce0bd0, algo=3, sg_mode=sg_mode@entry=true, acc_mode=acc_mode@entry=true)
      at ../hw/misc/aspeed_hace.c:224
  #2  0x00005555559bdbb8 in aspeed_hace_write (opaque=<optimized out>, addr=12, data=262488, size=<optimized out>)
      at ../hw/misc/aspeed_hace.c:358

This change doesn't fix much, but at least the guest
can't crash QEMU anymore. Instead it is still usable:

  uart:~$ hash test
  sha256_test
  tv[0]:hash_final error
  sha384_test
  tv[0]:hash_final error
  sha512_test
  tv[0]:hash_final error
  [00:00:06.278,000] <err> hace_global: HACE poll timeout
  [00:00:09.324,000] <err> hace_global: HACE poll timeout
  [00:00:12.261,000] <err> hace_global: HACE poll timeout
  uart:~$

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Delevoryas <peter@pjd.dev>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>