dlm: eliminate astparam type casting

Put lkb_astparam in a union with a dlm_user_args pointer to
eliminate a lot of type casting.

Signed-off-by: David Teigland <teigland@redhat.com>

diff --cc fs/dlm/debug_fs.c
Simple merge

diff --cc fs/dlm/dlm_internal.h
Simple merge

diff --cc fs/dlm/lock.c
Simple merge

diff --cc fs/dlm/memory.c
Simple merge

diff --cc fs/dlm/netlink.c
Simple merge

diff --cc fs/dlm/user.c
Simple merge