thermal: exynos: remove needless emul_temp_shift abstraction

reg->emul_temp_shift is used only in exynos_tmu_set_emulation()
and accessed only if TMU_SUPPORT_EMULATION flag is set.  This
flag is not set for Exynos4210 (reg->emul_temp_shift field is
not even assigned in exynos4210_tmu_registers and is assigned
to identical value for all other SoC types) so the abstraction
is not needed and can be removed.

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>