thermal: exynos: add ->tmu_initialize method

Add ->tmu_initialize method to struct exynos_tmu_data and
use it in exynos_tmu_initialize().  Then add ->tmu_initialize
implementations for Exynos4210, Exynos4412+ and Exynos5440.
Finally remove no longer needed reg->threshold_th[0,1],
reg->intclr_[fall,rise]_shift and reg->intclr_[rise,fall]_mask
abstractions.

There are more improvements available in the future on top
of this patch like merging HW_TRIP level setting with setting
of other levels for Exynos4412+ or adding separate method
for clearing IRQs using INTCLEAR register (for Exynos5420,
Exynos5260 and Exynos4412+).

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>