ACPI: APEI: rename ghes_init() with an "acpi_" prefix

ghes_init() sticks out in acpi_init() because it is the only functions
without an "acpi_" prefix.

Rename ghes_init with an "acpi_" prefix, then all looks fine.

Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>