x85: mptable: Move the mptable to the end of base RAM
x85: mptable: Move the mptable to the end of base RAM

Recent Linux kernel's fail to start if the mptable is at the start of
RAM (address 0x00). Avoid putting the mptable there so that crosvm can
boot 4.14+ kernels. The kernel scans the last kilobyte of RAM after the
first, move the mptable there.

Change-Id: Ia00f49e7a4cbd0fb3719c21b757e8fdca65584e8
Signed-off-by: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/780045

google/crosvm,google/crosvm,google/crosvm,google/crosvm