ARM: imx: Remove unused include of linux/of.h on mach-imx6sl.c

linux/of.h is NOT used on mach-imx6sl.c, remove it.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/mach-imx/mach-imx6sl.c

@@ -4,7 +4,6 @@
  */
 
 #include <linux/irqchip.h>
-#include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>