thermal: exynos: remove SoC type ifdefs

Maximum theoretical size saving (i.e. with only Exynos5410
SoC support enabled in kernel config so all SoC dependend
Exynos thermal driver code was dropped) is 4096 bytes so
there is no much sense in keeping these ifdefs (especially
given that they are useless once the driver gets updated to
use device tree).

While at it remove needless 'void *' casts.

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>