module: make module_address_lookup safe

module_address_lookup releases preemption then returns a pointer into
the module space.  The only user (kallsyms) copies the result, so just
do that under the preempt disable.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --cc include/linux/module.h
Simple merge

diff --cc kernel/kallsyms.c
Simple merge

diff --cc kernel/module.c
Simple merge