sh: don't pass saved userspace state to exception handlers

The compiler is permitted to generate code which overwrites the
parameters to a function.  If those parameters include the only saved
copy we have of userspace's registers, we're in trouble.

Signed-off-by: Bobby Bingham <koorogi@koorogi.info>
Cc: Paul Mundt <paul.mundt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>