ARM: mach-imx: tzic: Staticize *tzic_base

Fix the following sparse warning:

arch/arm/mach-imx/tzic.c:52:14: warning: symbol 'tzic_base' was not declared. Should it be static?

Also, remove the comment, as it does not apply for kernels newer than 3.2.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/tzic.c

@@ -49,7 +49,7 @@
 #define TZIC_SWINT	0x0F00	/* Software Interrupt Rigger Register */
 #define TZIC_ID0	0x0FD0	/* Indentification Register 0 */
 
-void __iomem *tzic_base; /* Used as irq controller base in entry-macro.S */
+static void __iomem *tzic_base;
 static struct irq_domain *domain;
 
 #define TZIC_NUM_IRQS 128