Virtual MFC codec's child devices must not be assigned to platform bus,
because they are allocated as raw 'struct device' and don't have the
corresponding 'platform' part. This fixes NULL pointer access revealed
recently by commit a66d9724 ("devres: Align data[] to
ARCH_KMALLOC_MINALIGN").

Fixes: c79667dd ("media: s5p-mfc: replace custom reserved memory handling code with generic one")
Reported-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>