[media] vivid: Don't mess with namespace adding a "get_format" function

[media] vivid: Don't mess with namespace adding a "get_format" function

This fixes a compilation error with allyesconfig:

drivers/media/platform/exynos-gsc/built-in.o: In function `get_format':
(.text+0x12f5): multiple definition of `get_format'
drivers/media/platform/vivid/built-in.o:(.text+0x4bf4): first defined here

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>