hw/arm/spitz: Move problematic nand_init() code to realize function

hw/arm/spitz: Move problematic nand_init() code to realize function

nand_init() does not only create the NAND device, it also realizes
the device with qdev_init_nofail() already. So we must not call
nand_init() from an instance_init function like sl_nand_init(),
otherwise we get superfluous NAND devices in the QOM tree after
introspecting the 'sl-nand' device. So move the nand_init() to the
realize function of 'sl-nand' instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1532006134-7701-1-git-send-email-thuth@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>