drm/i915/gvt: move structs intel_gvt_irq_info and intel_gvt_irq_map to interrupt.c

Structs intel_gvt_irq_info and intel_gvt_irq_map are not used outside of
interrupt.c. Hide them, and reduce includes.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230926121904.499888-4-jani.nikula@intel.com