Add "hw/qdev-core.h" to avoid when refactoring include/:

  softmmu/qtest.c:404:9: error: use of undeclared identifier 'NamedGPIOList'
        NamedGPIOList *ngl;
        ^

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220207082756.82600-5-f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>