ACPI: APEI: fix return value of __setup handlers

__setup() handlers should return 1 to indicate that the boot option
has been handled. Returning 0 causes a boot option to be listed in
the Unknown kernel command line parameters and also added to init's
arg list (if no '=' sign) or environment list (if of the form 'a=b').

Unknown kernel command line parameters "erst_disable
  bert_disable hest_disable BOOT_IMAGE=/boot/bzImage-517rc6", will be
  passed to user space.

 Run /sbin/init as init process
   with arguments:
     /sbin/init
     erst_disable
     bert_disable
     hest_disable
   with environment:
     HOME=/
     TERM=linux
     BOOT_IMAGE=/boot/bzImage-517rc6

Fixes: a3e2acc5 ("ACPI / APEI: Add Boot Error Record Table (BERT) support")
Fixes: a08f82d0 ("ACPI, APEI, Error Record Serialization Table (ERST) support")
Fixes: 9dc96664

 ("ACPI, APEI, HEST table parsing")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>