common/cmd_fitupd.c: restore corrupted file

This file got corrupted by the automatic editin of commit 1a459660 "Add
GPL-2.0+ SPDX-License-Identifier to source files"; restore the
opiginal content and manually insert the SPDX ID.

The bug was detected by running cppcheck, which reported:
[common/cmd_fitupd.c:8]: (error) Invalid number of character ({) when
these macros are defined: 'CONFIG_UPDATE_TFTP'.

Signed-off-by: Wolfgang Denk <wd@denx.de>

common/cmd_fitupd.c

-de <net.h>
-
-#if !defined(CONFIG_UPDATE_TFTP)
-#error "CONFIG_UPDATE_TFTP required"
-#endif
-
-static int do_fitupd(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
-{
-	ulong addr = 0Un the root directory of the source tree for details.
+/*
+ * (C) Copyright 2011
+ * Andreas Pretzsch, carpe noctem engineering, apr@cn-eng.de
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>