drivers: hwinfo: shell: fix error message when no hardware support

When there is no implementation for a particular hardware information
device, the API return -ENOSYS, while the hardware information shell
checks for -ENOTSUP. This returns a non-user friendly message:

  uart:~$ hwinfo devid
  Error: -88

The API can't be changed easily without breaking things, so let's change
the shell instead. This gives:

  uart:~$ hwinfo devid
  Not supported by hardware

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>