acpi: drop weak implementation of acpi_soc_get_bert_region

acpi_soc_get_bert_region only gets called when a chipset's Kconfig
selects the ACPI_BERT option in which case the chipset code needs to
implement this function. In the case of acpi_soc_get_bert_region not
being implemented, but ACPI_BERT being selected for a chipset this patch
changes the behavior from never generating a BERT ACPI table to a build
error which is more obvious and easier to catch.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Id479fce823d8534a7790f39125d1a2b3635fc029
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55277
Reviewed-by: Lance Zhao
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/acpi/acpi.c

@@ -1559,12 +1559,6 @@ unsigned long acpi_create_lpi_desc_ncst(acpi_lpi_desc_ncst_t *lpi_desc, uint16_t
 	return lpi_desc->header.length;
 }
 
-/* BERT helpers */
-__weak enum cb_err acpi_soc_get_bert_region(void **region, size_t *length)
-{
-	return CB_ERR;
-}
-
 unsigned long __weak fw_cfg_acpi_tables(unsigned long start)
 {
 	return 0;