[ARM] 3626/1: ARM EABI: fix syscall restarting

Patch from Nicolas Pitre

The RESTARTBLOCK case currently store some code on the stack to invoke
sys_restart_syscall.  However this is ABI dependent and there is a
mismatch with the way __NR_restart_syscall gets defined when the kernel
is compiled for EABI.

There is also a long standing bug in the thumb case since with OABI the
__NR_restart_syscall value includes __NR_SYSCALL_BASE which should not
be the case for Thumb syscalls.

Credits to Yauheni Kaliuta <yauheni.kaliuta@gmail.com> for finding the
EABI bug.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>