thermal: exynos: move IRQs clearing to exynos_tmu_initialize()

Move ->tmu_clear_irqs call from ->tmu_initialize method to
exynos_tmu_initialize().

There should be no functional changes caused by this patch.

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