x86/platform/intel-mid: Don't shadow error code of mp_map_gsi_to_irq()

When call mp_map_gsi_to_irq() and return its error code do not shadow it.
Note that 0 is not an error.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: http://lkml.kernel.org/r/20170119192425.189899-4-andriy.shevchenko@linux.intel.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>