acpi: Disable ACPI table override if securelevel is set

From the kernel documentation (initrd_table_override.txt):

  If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible
  to override nearly any ACPI table provided by the BIOS with an
  instrumented, modified one.

When securelevel is set, the kernel should disallow any unauthenticated
changes to kernel space. ACPI tables contain code invoked by the kernel, so
do not allow ACPI tables to be overridden if securelevel is set.

Signed-off-by: Linn Crosetto <linn@hpe.com>
static void __init trim_bios_range(void)
{
	/*
	 * A special case is the first 4Kb of memory;
	 * This is a BIOS owned area, not kernel ram, but generally
	 * not listed as such in the E820 table.
	 *
	 * This typically reserves additional memory (64KiB by default)
	 * since some BIOSes are known to corrupt low memory.  See the
	 * Kconfig help text for X86_RESERVE_LOW.
	 */
	e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);

	/*
	 * special case: Some BIOSen report the PC BIOS
	 * area (640->1Mb) as ram even though it is not.
	 * take them out.
	 */
	e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);

	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
}

static void __init trim_bios_range(void)
{
	/*
	 * A special case is the first 4Kb of memory;
	 * This is a BIOS owned area, not kernel ram, but generally
	 * not listed as such in the E820 table.
	 *
	 * This typically reserves additional memory (64KiB by default)
	 * since some BIOSes are known to corrupt low memory.  See the
	 * Kconfig help text for X86_RESERVE_LOW.
	 */
	e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);

	/*
	 * special case: Some BIOSen report the PC BIOS
	 * area (640->1Mb) as ram even though it is not.
	 * take them out.
	 */
	e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);

	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
}
