thermal: exynos: Use ARCH_HAS_BANDGAP config to know the supported soc's

This patch uses the recently added config sybmol ARCH_HAS_BANDGAP to enable
the TMU driver. This will allow adding support for new soc easily as now it
is the platform responsibility to enable this config symbol for a particular
soc.
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>

drivers/thermal/samsung/Kconfig

 config EXYNOS_THERMAL
 	tristate "Temperature sensor on Samsung EXYNOS"
-	depends on (ARCH_EXYNOS4 || ARCH_EXYNOS5)
+	depends on ARCH_HAS_BANDGAP
 	depends on CPU_THERMAL
 	help
 	  If you say yes here you get support for TMU (Thermal Management