target/i386/kvm: Remove x86_cpu_change_kvm_default() and 'kvm-cpu.h'

x86_cpu_change_kvm_default() was only used out of kvm-cpu.c by
the pc-i440fx-2.1 machine, which got removed. Make it static,
and remove its declaration. "kvm-cpu.h" is now empty, remove it.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20240617071118.60464-10-philmd@linaro.org>
2 files changed