[IA64] sync compat getdents

Add VERIFY_WRITE check in the beginning like compat_sys_getdents() (EINVAL vs
EFAULT).

Signed-off-by: Alexandr Andreev <aandreev@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>