ACPICA: Tables: Fix FADT dependency regression

Some logics actually relying on the existence of FADT, currently relies on
the number of loaded tables. This false dependency can easily trigger
regressions. One of them has been introduced by commit 8ec3f45907
(ACPICA: Tables: Fix global table list issues by removing fixed table).

The commit changing the fixed table indexes results in the change of FADT
table index, originally, it was 3 (thus the installed table count should be
greater than 4), while currently it is 0 (and the installed table count may
be 3).

This patch fixes this regression by cleaning up the code. Lv Zheng.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=105351
Fixes: 8ec3f45907 (ACPICA: Tables: Fix global table list issues by removing fixed table)
Reported-and-tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/tbutils.c

@@ -97,29 +97,6 @@ acpi_status acpi_tb_initialize_facs(void)
 }
 #endif				/* !ACPI_REDUCED_HARDWARE */
 
-/*******************************************************************************
- *
- * FUNCTION:    acpi_tb_tables_loaded
- *
- * PARAMETERS:  None
- *
- * RETURN:      TRUE if required ACPI tables are loaded
- *
- * DESCRIPTION: Determine if the minimum required ACPI tables are present
- *              (FADT, FACS, DSDT)
- *
- ******************************************************************************/
-
-u8 acpi_tb_tables_loaded(void)
-{
-
-	if (acpi_gbl_root_table_list.current_table_count >= 4) {
-		return (TRUE);
-	}
-
-	return (FALSE);
-}
-
 /*******************************************************************************
  *
  * FUNCTION:    acpi_tb_check_dsdt_header
@@ -392,7 +369,8 @@ acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
 		    ACPI_COMPARE_NAME(&acpi_gbl_root_table_list.
 				      tables[table_index].signature,
 				      ACPI_SIG_FADT)) {
-			acpi_tb_parse_fadt(table_index);
+			acpi_gbl_fadt_index = table_index;
+			acpi_tb_parse_fadt();
 		}
 
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