[IA64] fix personality(PER_LINUX32) performance issue

The patch aims to fix a performance issue for the syscall
personality(PER_LINUX32).

On IA-64 box, the syscall personality (PER_LINUX32) has poor performance
because it failed to find the Linux/x86 execution domain. Then it tried
to load the kernel module however it failed always and it used the default
execution domain PER_LINUX instead. Requesting kernel modules is very
expensive. It caused the performance issue. (see the function
lookup_exec_domain in kernel/exec_domain.c).

To resolve the issue, execution domain Linux/x86 is always registered in
initialization time for IA-64 architecture.

Signed-off-by: Xiaolan Huang <xiaolan.huang@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>