Revert "x86: Switch QEMU over to use the bochs driver"

Revert "x86: Switch QEMU over to use the bochs driver"

Unfortunately the bochs driver does not currently work with distros.
It causes a hang between grub menu selection and the OS displaying
something.

Preliminary investigation shows that GRUB does not jump to the kernel
at all.

This reproduces reliably.

This reverts commit 1e72522a94a8ea6a5aeec711984040941d553d74.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com> # qemu-x86_64
[Slightly modify the commit message about preliminary investigation]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>