thermal: exynos: remove TMU_SUPPORT_READY_STATUS flag

Replace TMU_SUPPORT_READY_STATUS flag check in
exynos_tmu_initialize() by an explicit check for a SoC type
(all SoC types except Exynos5440 have TMU_SUPPORT_READY_STATUS
flag set in their struct exynos_tmu_init_data instances).

This is a preparation for introducing per-SoC type tmu_initialize
method.

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>