gdb: update sim mips testsuite copyright exemption

The sim testsuite was reorganized last year, so update the path.

gdb/copyright.py

diff --git a/gdb/copyright.py b/gdb/copyright.py
index c4e6f94..0de15b8 100644
--- a/gdb/copyright.py
+++ b/gdb/copyright.py
@@ -412,7 +412,7 @@
     "sim/ppc/vm.h",
     "sim/ppc/hw_iobus.c",
     "sim/ppc/inline.h",
-    "sim/testsuite/sim/mips/mips32-dsp2.s",
+    "sim/testsuite/mips/mips32-dsp2.s",
 )
 
 if __name__ == "__main__":