ARM: OMAP2+: sparse: add missing function declarations

omap3xxx_restart() and omap44xx_restart() are global
functions declared in common.h. Include this file
in omap3-restart.c and omap4-restart.c to prevent
sparse warnings of type:

arch/arm/mach-omap2/omap4-restart.c:22:6: warning: symbol 'omap44xx_restart' was not declared. Should it be static?
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Reviewed-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/omap3-restart.c

@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/reboot.h>
 
+#include "common.h"
 #include "control.h"
 #include "prm.h"
 

arch/arm/mach-omap2/omap4-restart.c

@@ -9,6 +9,7 @@
 
 #include <linux/types.h>
 #include <linux/reboot.h>
+#include "common.h"
 #include "prm.h"
 
 /**