staging: exfat: use prandom_u32() for i_generation

Similar to commit 46c9a946 ("shmem: use monotonic time for i_generation")
we should not use the deprecated get_seconds() interface for i_generation.

prandom_u32() is the replacement used in other file systems.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Link: https://lore.kernel.org/r/20191108213257.3097633-2-arnd@arndb.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/exfat/exfat_super.c

@@ -26,7 +26,7 @@
 #include <linux/sched.h>
 #include <linux/fs_struct.h>
 #include <linux/namei.h>
-
+#include <linux/random.h>
 #include <linux/string.h>
 #include <linux/nls.h>
 #include <linux/mutex.h>
@@ -3363,7 +3363,7 @@ static int exfat_fill_inode(struct inode *inode, struct file_id_t *fid)
 	inode->i_uid = sbi->options.fs_uid;
 	inode->i_gid = sbi->options.fs_gid;
 	INC_IVERSION(inode);
-	inode->i_generation = get_seconds();
+	inode->i_generation = prandom_u32();
 
 	if (info.Attr & ATTR_SUBDIR) { /* directory */
 		inode->i_generation &= ~1;