sh: resume_kernel fix for kernel oops built with CONFIG_BKL_PREEMPT=y.

This patch fixes a problem within the SH implementation of resume_kernel code,
that implements in assembly the bulk of preempt_schedule_irq function without
taking care of the extra code needed to handle the BKL preemptible.

The patch basically consists of removing this asm code and calling the common
C implementation (see kernel/sched.c) as other archs do.

Another change is the missing 'cli' macro invocation at the beginning of
the resume_kernel.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>