accel/accel-cpu-target.h: Include missing 'cpu.h' header

accel/accel-cpu-target.h: Include missing 'cpu.h' header

CPU_RESOLVING_TYPE is declared per target in "cpu.h". Include
it (along with "qom/object.h") to avoid when moving code around:

  include/accel/accel-cpu-target.h:26:50: error: expected ')'
     26 | DECLARE_CLASS_CHECKERS(AccelCPUClass, ACCEL_CPU, TYPE_ACCEL_CPU)
        |                                                  ^
  include/accel/accel-cpu-target.h:23:33: note: expanded from macro 'TYPE_ACCEL_CPU'
     23 | #define TYPE_ACCEL_CPU "accel-" CPU_RESOLVING_TYPE
        |                                 ^
  include/accel/accel-cpu-target.h:26:1: note: to match this '('
     26 | DECLARE_CLASS_CHECKERS(AccelCPUClass, ACCEL_CPU, TYPE_ACCEL_CPU)
        | ^
  include/qom/object.h:196:14: note: expanded from macro 'DECLARE_CLASS_CHECKERS'
    196 |     { return OBJECT_GET_CLASS(ClassType, obj, TYPENAME); } \
        |              ^
  include/qom/object.h:558:5: note: expanded from macro 'OBJECT_GET_CLASS'
    558 |     OBJECT_CLASS_CHECK(class, object_get_class(OBJECT(obj)), name)
        |     ^
  include/qom/object.h:544:74: note: expanded from macro 'OBJECT_CLASS_CHECK'
    544 |     ((class_type *)object_class_dynamic_cast_assert(OBJECT_CLASS(class), (name), \
        |                                                                          ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250123234415.59850-13-philmd@linaro.org>