media: fimc-is: constify fimc_formats array

media: fimc-is: constify fimc_formats array

Pointers to elements of the static array "fimc_formats" with "struct
fimc_fmt" are passed all around to various calls, but all of them do not
modify pointed data.  Constify the pointers everywhere which at the end
allows to make static array "fimc_formats" const itself.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>