qdev: Add qdev_prop_set_array()

Instead of exposing the ugly hack of how we represent arrays in qdev (a
static "foo-len" property and after it is set, dynamically created
"foo[i]" properties) to boards, add an interface that allows setting the
whole array at once.

Once all internal users of devices with array properties have been
converted to use this function, we can change the implementation to move
away from this hack.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20231030114802.3671871-4-peter.maydell@linaro.org