thermal: exynos: simplify HW_TRIP level setting

thermal: exynos: simplify HW_TRIP level setting

Simplify HW_TRIP level setting in exynos_tmu_initialize() (don't
pretend that the current code is hardware and configuration
independent and just do SoC type check explicitly).  Then remove
no longer needed reg->threshold_[th2,th3_l0_shift] abstractions
(only assigned for Exynos5440 in exynos5440_tmu_registers) and
EXYNOS_MAX_TRIGGER_PER_REG define.

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>