MIPS: mips64: fix typos in copyright text of start.S

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

Conflicts:

	arch/mips/cpu/mips64/start.S

Signed-off-by: Tom Rini <trini@ti.com>

arch/mips/cpu/mips64/start.S

@@ -3,7 +3,7 @@
  *
  *  Copyright (c) 2003	Wolfgang Denk <wd@denx.de>
  *
-  * SPDX-License-Identifier:	GPL-2.0+
+ * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <asm-offsets.h>