x86: sysreset: Set up LPC only after relocation

Probing LPC can cause PCI enumeration to take place, which significantly
increases pre-relocation memory usage. Also, LPC is somtimes enabled
directly by SPL.

Adjust the logic to probe the LPC only after relocation. This allows
chromebook_link64 to start up without a much larger
CONFIG_SYS_MALLOC_F_LEN value.

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