x86: fsp: Introduce CONFIG_FSP_USE_UPD Kconfig option

Not every FSP supports UPD, thus we introduce a Kconfig option
CONFIG_FSP_USE_UPD and use it to wrap these common UPD handling
codes in fsp_support.c.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>