objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns

Fix the following objtool warning during build time:

  fs/bcachefs/btree_cache.o: warning: objtool: btree_node_lock.constprop.0() falls through to next function bch2_recalc_btree_reserve()
  fs/bcachefs/btree_update.o: warning: objtool: bch2_trans_update_get_key_cache() falls through to next function need_whiteout_for_snapshot()

bch2_trans_unlocked_or_in_restart_error() is an Obviously Correct (tm)
panic() wrapper, add it to the list of known noreturns.

Fixes: b3188820 ("bcachefs: bch2_trans_verify_not_unlocked_or_in_restart()")
Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/r/20250218064230.219997-1-youling.tang@linux.dev


Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>