[PATCH] x86-64: Fix PTRACE_[SG]ET_THREAD_AREA regression with ia32 emulation.

ptrace(PTRACE_[SG]ET_THREAD_AREA) calls from ia32 code
should be passed onto the x86_64 implementation.

The default case in sys32_ptrace used to call to sys_ptrace(), but is
now EINVAL.  This patch fixes a regression caused by that changed.

Signed-off-by: Mike McCormack <mike@codeweavers.com>
Signed-off-by: Andi Kleen <ak@suse.de>