ARM: rmobile: Enable CONFIG_SYS_FLASH_PROTECTION

Enable CONFIG_SYS_FLASH_PROTECTION on Salvator-X(S), ULCB, Ebisu,
which means the Spansion HF PPB protection bits can be operated
using the 'protect' U-Boot command.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>