ACPI / APEI: Remove X86 redundant dependency for APEI GHES.

ACPI_APEI already depends on X86, so there is no need to define
such dependency for ACPI_APEI_GHES (Generic Hardware Error Source)
again.

Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>