Fix Byt CB Bootup on SeaBIOS when using coreboot

[CE1CECL]

This patch helps fix the internal eMMC card when booting from it with the MrChromebox custom coreboot distro. If this patch isn't applied, the OS cannot boot off of it, and if you boot from USB, then you will get spamming errors in dmesg. This also doesn't show on Windows PE if you do not apply this, and it will be very slow to boot, or to even use. Note that this SMM variable is currently only in the MrChromebox coreboot distro at the moment, and is used by his EDK2 distro as well. Also the line added in this patch should not be added to CBFS booting, so we can assume that the next payload woll do the same thing, like if we chainload SeaBIOS to EDK2. Also this is a dirty patch and should not be sent to mainline SeaBIOS and people hope for it to be removed with a coreboot fix anyways, when it isn't needed in EDK2 as well to boot or use. Tested only on GOOGLE Enguarde at the moment. MrChromebox = Matt DeVillier Byt = Intel Bay Trail CB = ChromeBook (and other Chrome OS Devices like Chromebox)