thermal: exynos: remove separate exynos_tmu.h header file

exynos_tmu.h is used only by exynos_tmu.c so there is no need
for a separate include file.

Also while at it remove no longer needed cpu_cooling.h include.

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>