core_pattern is not actually protected and hasn't been
ever since we introduced procfs support for sysctl -- a
_long_ time. Don't take it here either.

Also nothing inside do_coredump appears to require bkl
protection.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
[ remove smp_lock.h headers ]
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>