firewire: core: add helper functions to convert to parent resource structure

firewire: core: add helper functions to convert to parent resource structure

All of local resource structure commonly have data of client_resource type
in its first member. This design sometimes requires usage of
container_of to retrieve parent structure by the first member.

This commit adds some helper functions for this purpose.

Link: https://lore.kernel.org/r/20240812235210.28458-3-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>