V4L/DVB (7898): Fix VIDEO_MEDIA Kconfig logic

If one of DVB_CORE or VIDEO_DEV is a module, the modules that can be used by
both DVB and V4L cores should also be a module, otherwise, it will break its
dependencies. This Kconfig logic implements the following:

CONFIG_VIDEO_DEV        CONFIG_DVB_CORE         CONFIG_VIDEO_MEDIA
        N                       N                       N
        N                       M                       M
        N                       Y                       Y
        M                       N                       M
        M                       M                       M
        M                       Y                       M
        Y                       N                       Y
        Y                       M                       M
        Y                       Y                       Y

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>