sim-se: Ignore chmod syscall

chmod caused crashes in certain MIOpen apps with the newer
version of MIOpen used in the Dockerfile. Ignoring it allows
those apps to finish.

Change-Id: If8d144d64f76ae04f384ebf983024c571b26875e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30534
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/x86/linux/process.cc

@@ -347,7 +347,7 @@ static SyscallDescTable<X86_64LinuxProcess::SyscallABI> syscallDescs64 = {
     {  87, "unlink", unlinkFunc },
     {  88, "symlink", symlinkFunc },
     {  89, "readlink", readlinkFunc },
-    {  90, "chmod" },
+    {  90, "chmod", ignoreFunc },
     {  91, "fchmod" },
     {  92, "chown" },
     {  93, "fchown" },