Revert "firewire: core: disable bus management work temporarily during updating topology"

This reverts commit abe71591.

The bus manager work item acquires the spin lock of fw_card again, thus
no need to serialize it against fw_core_handle_bus_reset().

Link: https://lore.kernel.org/r/20250924131823.262136-3-o-takashi@sakamocchi.jp


Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>