sh: Add a few missing irqflags tracing markers.

save_regs contains an SR modification without an irqflags annotation,
which resulted in a missing TRACE_IRQS_OFF in the interrupt exception
path on SH-3/SH4.

I've also moved the TRACE_IRQS_OFF/ON annotation when returning from the
interrupt to just before we call __restore_all. This seems like the most
logical place to put this because the annotation is for when we restore
the SR register so we should delay the annotation until as last as
possible.

We were also missing a TRACE_IRQS_OFF in resume_kernel when
CONFIG_PREEMPT is enabled.

The end result is that this fixes up the lockdep engine debugging support
with CONFIG_PREEMPT enabled on all SH-3/4 parts.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>