udf: convert udf_stamp_to_time and udf_time_to_stamp to use timestamps

* kernel_timestamp type was almost unused - only callers of udf_stamp_to_time
and udf_time_to_stamp used it, so let these functions handle endianness
internally and don't clutter code with conversions

* rename udf_stamp_to_time to udf_disk_stamp_to_time
  and udf_time_to_stamp to udf_time_to_disk_stamp

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index b277524..2cb2f5d 100644
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -222,7 +222,8 @@
 extern uint16_t udf_crc(const uint8_t *, uint32_t, uint16_t);
 
 /* udftime.c */
-extern struct timespec *udf_stamp_to_time(struct timespec *dest, kernel_timestamp src);
-extern kernel_timestamp *udf_time_to_stamp(kernel_timestamp *dest, struct timespec src);
+extern struct timespec *udf_disk_stamp_to_time(struct timespec *dest,
+						timestamp src);
+extern timestamp *udf_time_to_disk_stamp(timestamp *dest, struct timespec src);
 
 #endif				/* __UDF_DECL_H */