hw/arm/xlnx-versal: Include missing 'cpu.h' header

hw/arm/xlnx-versal: Include missing 'cpu.h' header

include/hw/arm/xlnx-versal.h uses the ARMCPU structure which
is defined in the "target/arm/cpu.h" header. Include it in
order to avoid when refactoring unrelated headers:

  In file included from hw/arm/xlnx-versal-virt.c:20:
  include/hw/arm/xlnx-versal.h:62:23: error: array has incomplete element type 'ARMCPU' (aka 'struct ArchCPU')
              ARMCPU cpu[XLNX_VERSAL_NR_ACPUS];
                        ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240118200643.29037-5-philmd@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>