btrfs: locking: remove all the blocking helpers

[ Upstream commit ac5887c8 ]

Now that we're using a rw_semaphore we no longer need to indicate if a
lock is blocking or not, nor do we need to flip the entire path from
blocking to spinning.  Remove these helpers and all the places they are
called.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 44f52bbe ("btrfs: fix use-after-free when COWing tree bock and tracing is enabled")
Signed-off-by: Sasha Levin <sashal@kernel.org>