arm: armv7: omap3: Fix restore sequence in lowlevel_init

The restore sequence in lowlevel_init was in the wrong order,
causing lr to lose its original value and be set equal to ip
instead. Also, its use of the stack clashes with that of
s_init, so move the s_init call after the restore and turn
it  into a tail-optimized branch.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Tested-by: Jeroen Hofstee <jeroen@myspectrum.nl>