There are three tuners that depend on some functions inside
V4L2 core:

	$ git grep -l -E 'v4l2_[0-9a-zA-Z_]+\(' drivers/media/tuners/
	drivers/media/tuners/e4000.c
	drivers/media/tuners/fc2580.c
	drivers/media/tuners/msi001.c

Make them dependent of VIDEO_V4L2, as otherwise, this would happen:

	on x86_64:
	CONFIG_VIDEO_V4L2=m
	CONFIG_MEDIA_TUNER_E4000=y

	ld: drivers/media/tuners/e4000.o: in function `e4000_remove':
	e4000.c:(.text+0x34): undefined reference to `v4l2_ctrl_handler_free'
	ld: drivers/media/tuners/e4000.o: in function `e4000_probe':
	e4000.c:(.text+0x16c1): undefined reference to `v4l2_ctrl_handler_init_class'
	ld: e4000.c:(.text+0x16eb): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x1731): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x1762): undefined reference to `v4l2_ctrl_auto_cluster'
	ld: e4000.c:(.text+0x178c): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x17d6): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x1804): undefined reference to `v4l2_ctrl_auto_cluster'
	ld: e4000.c:(.text+0x182e): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x1878): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x18a6): undefined reference to `v4l2_ctrl_auto_cluster'
	ld: e4000.c:(.text+0x18d0): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x191a): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x1948): undefined reference to `v4l2_ctrl_auto_cluster'
	ld: e4000.c:(.text+0x1972): undefined reference to `v4l2_ctrl_new_std'
	ld: e4000.c:(.text+0x19a6): undefined reference to `v4l2_ctrl_handler_free'
	ld: e4000.c:(.text+0x1a2a): undefined reference to `v4l2_i2c_subdev_init'
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>