[IA64] update generic_defconfig to support sn2.

This patch changes the generic_defconfig so it works on all sn2
platforms I have access to.  There is only one support configuration
which was not tested and that configuration is only a combination of two
tested configurations.  With this patchset applied, a generic kernel can
be booted on either a RHEL 5.2, RHEL5.3, or SLES10 SP1 root and operate.
All features needed by SGI's ProPack are also working.  I have not
tested all features of RHEL or SLES, but they do at least boot.

Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>