thermal: exynos: remove TMU_SUPPORT_FALLING_TRIP flag

Replace TMU_SUPPORT_FALLING_TRIP flag check in
exynos[4210,5440]_tmu_control() by an explicit check
for a SoC type (all SoC types except Exynos4210 have
TMU_SUPPORT_FALLING_TRIP flag set in their struct
exynos_tmu_init_data instances).

There should be no functional changes caused by this patch.

Cc: Amit Daniel Kachhap <amit.daniel@samsung.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>