[S390] sparse: fix sparse warnings about missing prototypes

Add prototypes and includes for functions used in different modules.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/ipl.c

@@ -27,6 +27,7 @@
 #include <asm/sclp.h>
 #include <asm/sigp.h>
 #include <asm/checksum.h>
+#include "entry.h"
 
 #define IPL_PARM_BLOCK_VERSION 0