staging: zram: handle mem suffixes in disk size zram_sysfs parameter

Use memparse() to allow mem suffixes in disksize sysfs number.
Examples:
    echo 256K > /sys/block/zram0/disksize
    echo 512M > /sys/block/zram0/disksize
    echo 1G > /sys/block/zram0/disksize
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zram/zram_sysfs.c

@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/genhd.h>
 #include <linux/mm.h>
+#include <linux/kernel.h>
 
 #include "zram_drv.h"
 
@@ -54,13 +55,12 @@ static ssize_t disksize_show(struct device *dev,
 static ssize_t disksize_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
-	int ret;
 	u64 disksize;
 	struct zram *zram = dev_to_zram(dev);
 
-	ret = kstrtoull(buf, 10, &disksize);
-	if (ret)
-		return ret;
+	disksize = memparse(buf, NULL);
+	if (!disksize)
+		return -EINVAL;
 
 	down_write(&zram->init_lock);
 	if (zram->init_done) {