ACPI / APEI: fix error return code in ghes_probe()

Fix to return a negative error code in the acpi_gsi_to_irq() and
request_irq() error handling case instead of 0, as done elsewhere
in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Reviewed-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>