ARM: s3c: Cleanup from old plat-samsung include

The arch/arm/plat-samsung/ was removed and merged into
arch/arm/mach-s3c/ so the include path is not needed anymore.

Fixes: 71b9114d ("ARM: s3c: move into a common directory")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200821074251.26798-1-krzk@kernel.org

arch/arm/mach-s3c/Makefile.s3c64xx

@@ -3,8 +3,8 @@
 # Copyright 2008 Openmoko, Inc.
 # Copyright 2008 Simtec Electronics
 
-ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include -I$(srctree)/arch/arm/plat-samsung/include
-asflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include -I$(srctree)/arch/arm/plat-samsung/include
+ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include
+asflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include
 
 # PM