sandbox: fix return type of os_filesize()

Given a file ../img of size 4294967296 with GPT partition table and
partitions:

=> host bind 0 ../img
=> part list host 0
Disk host-0.blk not ready

The cause is os_filesize() returning int. File sizes must use off_t.

Correct all uses of os_filesize() too.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/block/host_dev.c b/drivers/block/host_dev.c
index 5885fc3..6442241 100644
--- a/drivers/block/host_dev.c
+++ b/drivers/block/host_dev.c
@@ -24,7 +24,8 @@
 	struct host_sb_plat *plat = dev_get_plat(dev);
 	struct blk_desc *desc;
 	struct udevice *blk;
-	int ret, fd, size;
+	int ret, fd;
+	off_t size;
 	char *fname;
 
 	if (!filename)