ACPI / watchdog: Print out error number when device creation fails

If the platform device creation fails for whichever reason the driver
prints out something like:

  [    0.978837] ACPI: watchdog: Failed to create platform device

However, that is quite confusing and does not include any information
why it failed. To make it more understandable, reword it like:

  [    0.978837] ACPI: watchdog: Device creation failed: -16

Which tells that we failed to create the watchdog device because some of
the resources were already reserved (-EBUSY).

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>