lockd: Relocate nlmsvc_unlock API declarations

lockd: Relocate nlmsvc_unlock API declarations

The nlmsvc_unlock_all_by_sb() and nlmsvc_unlock_all_by_ip()
functions are part of lockd's external API, consumed by other
kernel subsystems. Their declarations currently reside in
linux/lockd/lockd.h alongside internal implementation details,
which blurs the boundary between lockd's public interface and
its private internals.

Moving these declarations to linux/lockd/bind.h groups them
with other external API functions and makes the separation
explicit. This clarifies which functions are intended for
external use and reduces the risk of internal implementation
details leaking into the public API surface.

Build-tested with allyesconfig; no functional changes.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>