Patch from Nicolas Pitre

This patch adds the required code to support both user space ABIs at
the same time. A second syscall table is created to include legacy ABI
syscalls that need an ABI compat wrapper.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>