x86_64-tune: fix KVM qemu options

x86_64-tune: fix KVM qemu options

When using runqemu with KVM enabled, qemuboot.conf uses QB_CPU_KVM_x86
and QB_CPU_KVM_x86-64 instead of QB_CPU_qemux86-64. Without this fix,
the boot fails because the generic KVM CPUs don't support what Nehalem
does.

Change-Id: Ic7d160528c5aebfb835362f3ad3c2da2dc44c2c4
Signed-off-by: Martin Kelly <mkelly@xevo.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/9329
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>