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>
acpi_status acpi_os_signal(u32 function, void *info)
{
	switch (function) {
	case ACPI_SIGNAL_FATAL:
		printk(KERN_ERR PREFIX "Fatal opcode executed\n");
		break;
	case ACPI_SIGNAL_BREAKPOINT:
		/*
		 * AML Breakpoint
		 * ACPI spec. says to treat it as a NOP unless
		 * you are debugging.  So if/when we integrate
		 * AML debugger into the kernel debugger its
		 * hook will go here.  But until then it is
		 * not useful to print anything on breakpoints.
		 */
		break;
	default:
		break;
	}

	return AE_OK;
}

acpi_status acpi_os_signal(u32 function, void *info)
{
	switch (function) {
	case ACPI_SIGNAL_FATAL:
		printk(KERN_ERR PREFIX "Fatal opcode executed\n");
		break;
	case ACPI_SIGNAL_BREAKPOINT:
		/*
		 * AML Breakpoint
		 * ACPI spec. says to treat it as a NOP unless
		 * you are debugging.  So if/when we integrate
		 * AML debugger into the kernel debugger its
		 * hook will go here.  But until then it is
		 * not useful to print anything on breakpoints.
		 */
		break;
	default:
		break;
	}

	return AE_OK;
}
