s390: remove couple of duplicate includes

Removing couple of duplicate includes, found by "make includecheck".
That leaves 1 duplicate include in arch/s390/kernel/entry.S, which is
there for a reason (it includes generated asm/syscall_table.h twice).
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/dasd_diag.c

@@ -27,7 +27,6 @@
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/vtoc.h>
-#include <asm/diag.h>
 
 #include "dasd_int.h"
 #include "dasd_diag.h"

drivers/s390/net/qeth_l2_main.c

@@ -21,7 +21,6 @@
 #include <linux/list.h>
 #include <linux/hash.h>
 #include <linux/hashtable.h>
-#include <linux/string.h>
 #include <asm/setup.h>
 #include "qeth_core.h"
 #include "qeth_l2.h"