x86: baytrail: Change "fsp, mrc-init-tseg-size" default value to 1

The default value of "fsp,mrc-init-tseg-size" should be 1 (1MB) per
FSP default settings. 0 is not valid.

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