[media] s5p-fimc: Change the driver directory name to exynos4-is

The s5p-fimc directory now contains drivers for multiple IP blocks
found in multiple Samsung application processors. This includes FIMC
(CAMIF), MIPI CSIS and FIMC LITE. FIMC-IS (Imaging Subsystem) driver
is going to be put into same directory. Hence we rename it to
exynos4-is as s5p-fimc was only relevant for early version of this
driver, when it only supported FIMC IP block.

The imaging subsystem drivers for Exynos4 SoC series and S5PV210 will
be included in drivers/media/platform/exynos4-is directory, with some
modules shared with exynos5 series, while the rest of exynos5 specific
modules will find their home in drivers/media/platform/exynos5-is.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>