s390/cmm: make copy_from_user() invocation provably correct

Get rid of these two warnings:

In function 'copy_from_user',
    inlined from 'cmm_timeout_handler' at arch/s390/mm/cmm.c:310:
      uaccess.h:303: warning: call to 'copy_from_user_overflow' declared
      with attribute warning: copy_from_user() buffer size is not provably
      correct
In function 'copy_from_user',
    inlined from 'cmm_pages_handler' at arch/s390/mm/cmm.c:270:
      uaccess.h:303: warning: call to 'copy_from_user_overflow' declared
      with attribute warning: copy_from_user() buffer size is not provably
      correct

Change the "len" type to unsigned int, so we can make sure that there is no
buffer overflow. This also generates less code.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/cmm.c

@@ -257,8 +257,8 @@ static int cmm_pages_handler(ctl_table *ctl, int write, void __user *buffer,
 			     size_t *lenp, loff_t *ppos)
 {
 	char buf[16], *p;
+	unsigned int len;
 	long nr;
-	int len;
 
 	if (!*lenp || (*ppos && !write)) {
 		*lenp = 0;
@@ -298,7 +298,7 @@ static int cmm_timeout_handler(ctl_table *ctl, int write,  void __user *buffer,
 {
 	char buf[64], *p;
 	long nr, seconds;
-	int len;
+	unsigned int len;
 
 	if (!*lenp || (*ppos && !write)) {
 		*lenp = 0;