score: add missing #includes

Files that define a global function should #include the
header with its declaration to make sure that the prototypes
do not diverge.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/score/kernel/process.c

@@ -24,6 +24,9 @@
  */
 
 #include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/elfcore.h>
+#include <linux/pm.h>
 
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);