omap2+: wdt: trivial sparse fixes

omap2_wd_timer_disable is declared in wdtimer.h and used by hwmod
function pointers for usage, the header inclusion is necessary
to ensure that the prototype and function remains consistent.
omap_wdt_latency is passed as a pointer and does not need global scope

Fixes sparse warnings:
arch/arm/mach-omap2/devices.c:981:31: warning: symbol 'omap_wdt_latency' was not declared. Should it be static?
arch/arm/mach-omap2/wd_timer.c:27:5: warning: symbol 'omap2_wd_timer_disable' was not declared. Should it be static?

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/devices.c

@@ -978,7 +978,7 @@ static int __init omap2_init_devices(void)
 arch_initcall(omap2_init_devices);
 
 #if defined(CONFIG_OMAP_WATCHDOG) || defined(CONFIG_OMAP_WATCHDOG_MODULE)
-struct omap_device_pm_latency omap_wdt_latency[] = {
+static struct omap_device_pm_latency omap_wdt_latency[] = {
 	[0] = {
 		.deactivate_func = omap_device_idle_hwmods,
 		.activate_func   = omap_device_enable_hwmods,

arch/arm/mach-omap2/wd_timer.c

@@ -13,6 +13,8 @@
 
 #include <plat/omap_hwmod.h>
 
+#include "wd_timer.h"
+
 /*
  * In order to avoid any assumptions from bootloader regarding WDT
  * settings, WDT module is reset during init. This enables the watchdog