ARM: at91: fix warnings in pm.c

Fix a pair of missing statics on un-exported functions and
include <linux/platform_data/atmel.h> to provide the declaration
of at91_suspend_entering_slow_clock() to fix the following
sparse warnings:

arch/arm/mach-at91/pm.c:127:5: warning: symbol 'at91_suspend_entering_slow_clock' was not declared. Should it be static?
arch/arm/mach-at91/pm.c:358:6: warning: symbol 'at91rm9200_idle' was not declared. Should it be static?
arch/arm/mach-at91/pm.c:367:6: warning: symbol 'at91sam9_idle' was not declared. Should it be static?
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

arch/arm/mach-at91/pm.c

@@ -22,6 +22,7 @@
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
+#include <linux/platform_data/atmel.h>
 #include <linux/io.h>
 #include <linux/clk/at91_pmc.h>
 
@@ -355,7 +356,7 @@ static __init void at91_dt_ramc(void)
 	at91_pm_set_standby(standby);
 }
 
-void at91rm9200_idle(void)
+static void at91rm9200_idle(void)
 {
 	/*
 	 * Disable the processor clock.  The processor will be automatically
@@ -364,7 +365,7 @@ void at91rm9200_idle(void)
 	writel(AT91_PMC_PCK, pmc + AT91_PMC_SCDR);
 }
 
-void at91sam9_idle(void)
+static void at91sam9_idle(void)
 {
 	writel(AT91_PMC_PCK, pmc + AT91_PMC_SCDR);
 	cpu_do_idle();