x86: Introduce USE_EARLY_BOARD_INIT option

Introduce USE_EARLY_BOARD_INIT option and select it by the actual users.

Cc: George McCollister <george.mccollister@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>