[IA64] remove unnecessary nfs includes from sys_ia32.c

Compilation of 2.6.25-rc2-mm1 on ia64 generates many warnings.

IA64 support 2 ELF format (IA64 binary and IA32 binary),
thus if 2 elf related header included, cause many warning or error.

about 2 week ago, J. Bruce Fields proposed this problem fixed patch.
(http://marc.info/?l=linux-ia64&m=120329313305695&w=2)

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>