ACPI S3: Remove conflicting local acpi_get_sleep_type()

ACPI S3: Remove conflicting local acpi_get_sleep_type()

We now require EARLY_CBMEM_INIT and romstage_handoff to
support HAVE_ACPI_RESUME. Thus acpi_handoff_wakeup() would
never call an externally defined acpi_get_sleep_type().

Name _sleep_type() was also inapproriate here, as it referred
to hardware-dependent SLP_TYP field of PM1CNT but still
returned ACPI_Sx value instead.

Change-Id: I8dc130f1e86dd7e96922d546f0ae9713188336cd
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/21397
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>