thermal: exynos: remove TMU_SUPPORT_TRIM_RELOAD flag

Replace TMU_SUPPORT_TRIM_RELOAD flag check in exynos_tmu_initialize()
by an explicit check for a SoC type (only Exynos3250, Exynos4412 and
Exynos5250 have TMU_SUPPORT_READY_STATUS flag set in their struct
exynos_tmu_init_data instances).  Please note that this requires
adding separate SoC type for Exynos5420 so it doesn't get mistaken
with Exynos5250.

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>