MN10300: Fix the preemption resume_kernel() routine

Fix the preemption resume_kernel() routine by inverting the test to see
whether interrupts are off (IM7 is all enabled, not all disabled).

Furthermore, interrupts should be disabled on entry to resume_kernel() so that
they're correctly set for jumping to restore_all() and doing the need
reschedule test.

Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>