MTP: Use a fd instead of a file path in file transfer ioctls.

This restricts the driver to the client's permissions when copying files
to avoid potential security problems.

Change-Id: I9b3151168d334fe4374875804d4ba82bef44db3b
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/media/mtp/f_mtp.h b/media/mtp/f_mtp.h
index 82015a0..c1c9aef 100644
--- a/media/mtp/f_mtp.h
+++ b/media/mtp/f_mtp.h
@@ -24,10 +24,8 @@
 
 
 struct mtp_file_range {
-	/* path for file to transfer */
-	const char	*path;
-	/* strlen(path) */
-	int			path_length;
+	/* file descriptor for file to transfer */
+	int			fd;
 	/* offset in file for start of transfer */
 	loff_t  	offset;
 	/* number of bytes to transfer */