[IA64] remove use of asm/segment.h

Removed IA64 architecture specific users of asm/segment.h
The removal of asm-ia64/segment.h itself can wait until all
of the kernel source has been purged of references.

Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>