boards: x86: enable MULTIBOOT_MEMMAP
boards: x86: enable MULTIBOOT_MEMMAP

QEMU provides multiboot information by default so we can
use the provided memory map to mark reserved physical
memory. Note that 64-bit requires Multiboot2 which
currently both Zephyr and QEMU do not support, hence
it's not enabled for qemu_x86_64.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr