s390/xpram: don't modify module parameters

During parsing of the sizes array the pointer to the particular
string is lost. Keep it by using an extra pointer to store the end
position of the parsed string. Keeping these parameters accessible
can be helpful for debugging purposes and for userspace reading
the parameters at runtime via sysfs. Also this will ensure that the
memory is freed at module unload time.
Reported-by: Michael Veigel <veigel@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/xpram.c

@@ -257,6 +257,7 @@ static int __init xpram_setup_sizes(unsigned long pages)
 	unsigned long mem_needed;
 	unsigned long mem_auto;
 	unsigned long long size;
+	char *sizes_end;
 	int mem_auto_no;
 	int i;
 
@@ -275,8 +276,8 @@ static int __init xpram_setup_sizes(unsigned long pages)
 	mem_auto_no = 0;
 	for (i = 0; i < xpram_devs; i++) {
 		if (sizes[i]) {
-			size = simple_strtoull(sizes[i], &sizes[i], 0);
-			switch (sizes[i][0]) {
+			size = simple_strtoull(sizes[i], &sizes_end, 0);
+			switch (*sizes_end) {
 			case 'g':
 			case 'G':
 				size <<= 20;