ext4: fix unsigned long long printk warning in super.c

sparc64 allmodconfig:

fs/ext4/super.c: In function `lifetime_write_kbytes_show':
fs/ext4/super.c:2174: warning: long long unsigned int format, long unsigned int arg (arg 4)
fs/ext4/super.c:2174: warning: long long unsigned int format, long unsigned int arg (arg 4)
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

@@ -2174,9 +2174,9 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
 	struct super_block *sb = sbi->s_buddy_cache->i_sb;
 
 	return snprintf(buf, PAGE_SIZE, "%llu\n",
-			sbi->s_kbytes_written + 
+			(unsigned long long)(sbi->s_kbytes_written +
 			((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
-			  EXT4_SB(sb)->s_sectors_written_start) >> 1));
+			  EXT4_SB(sb)->s_sectors_written_start) >> 1)));
 }
 
 static ssize_t inode_readahead_blks_store(struct ext4_attr *a,