firewire: ohci: use devres for misc DMA buffer

The 1394 OHCI driver allocates a DMA coherent buffer for multi-purposes.
The buffer is split into three region for specific purposes; i.e. 1/4 for
context descriptors of AR request and response as well as 1/2 for self
ID handling.

This commit uses managed device resource to maintain the lifetime of
buffer.

Link: https://lore.kernel.org/r/20230604054451.161076-5-o-takashi@sakamocchi.jp


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