i915: fix DRM_I915_GVT_KVMGT dependencies

i915: fix DRM_I915_GVT_KVMGT dependencies

Depending on x86 and KVM is not enough, as the kvm helper functions
that get called here are controlled by CONFIG_KVM_X86, which is
disabled if both KVM_INTEL and KVM_AMD are turned off.

ERROR: modpost: "kvm_write_track_remove_gfn" [drivers/gpu/drm/i915/kvmgt.ko] undefined!
ERROR: modpost: "kvm_page_track_register_notifier" [drivers/gpu/drm/i915/kvmgt.ko] undefined!
ERROR: modpost: "kvm_page_track_unregister_notifier" [drivers/gpu/drm/i915/kvmgt.ko] undefined!
ERROR: modpost: "kvm_write_track_add_gfn" [drivers/gpu/drm/i915/kvmgt.ko] undefined!

Change the dependency to CONFIG_KVM_X86 instead.

Fixes: ea4290d77bda ("KVM: x86: leave kvm.ko out of the build if no vendor module is requested")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20241015152157.2955229-1-arnd@kernel.org
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>