x86: apl: Set the correct boot mode in the FSP-M code

If there is MRC information we should run FSP-M with a different
boot_mode flag since it is supposed to do a 'fast path' through the
memory init. Fix this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>