ACPI: sysfs: Refactor param_get_trace_state() to drop dead code

The param_get_trace_state() has a few dead code issues:
 - 'return 0;' is never reachable
 - a few 'else' keywords are redundant

Refactor param_get_trace_state() to drop dead code.

Note, leave one 'else' in order to have the best readability.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>