ARM: S5P: Remove redundant selection PLAT_S5P for S5PC100, S5PV210 and S5PV310

The selection PLAT_S5P is selected with plat-s5p/Kconfig.
So remove it form each CPU_S5PXXXX config.
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[kgene.kim@samsung.com: edited title]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s5pc100/Kconfig

@@ -9,7 +9,6 @@ if ARCH_S5PC100
 
 config CPU_S5PC100
 	bool
-	select PLAT_S5P
 	select S5P_EXT_INT
 	select S3C_PL330_DMA
 	help

arch/arm/mach-s5pv210/Kconfig

@@ -11,7 +11,6 @@ if ARCH_S5PV210
 
 config CPU_S5PV210
 	bool
-	select PLAT_S5P
 	select S3C_PL330_DMA
 	select S5P_EXT_INT
 	help

arch/arm/mach-s5pv310/Kconfig

@@ -11,7 +11,6 @@ if ARCH_S5PV310
 
 config CPU_S5PV310
 	bool
-	select PLAT_S5P
 	help
 	  Enable S5PV310 CPU support