linux-samsung-kminilte: add flashlight support (MR 1150)

These changes enable the flashlight LED driver (fled_rt5033), and add
support for switching the light on and off from userspace.

In more detail:

* CONFIG_FLED_RT5033 enables the flashlight driver
* CONFIG_VIDEO_EXYNOS_FIMC_IS is required for the flashlight driver to
  compile (there seems to be a lot of cross-dependency between the two
  drivers)
* patch 0001 fixes the use of usleep (which no longer exists), to make
  the kernel compile with those settings

With these changes, /sys/class/flashlight/rt-flash-led shows up in
sysfs, but it's only possible to control the brightness of the LED,
not to switch it on.

Patch 0002 is what actually makes the flashlight usable: it makes
the /sys/class/flashlight/rt-flash-led/mode file writable.

Writing "Torch" there enables the flashlight, writing "Off" disables
it again. "Mixed" mode works like "Torch" as well. I have not figured
out yet how to trigger the camera flash, so setting the mode to
"Flash" is possible, albeit pointless.