m68knommu: simplify ColdFire resume code

It is useless to preserve THREAD_SR in `resume'.  The real user's sr
is actually in the stack.  We also don't need to disable interrupts :
we'll never be in an invalid state, the sp switch is atomic.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>